Is It Really Necessary To Send One’s Housing To A Dealer For Annual Maintenance?

Housing manufacturers recommend sending your housing for an overhaul service every one to two years. But, is this really necessary? Or can one just do IRAN-Inspect and repair as needed?
 After I flooded my first dSLR housing in 2014, I sent it to one of the USA’s three top dealers for overhaul, after which I noticed several of the buttons were still either rusty or dirty. I complained to the dealer, who replied the housing maintenance was not done in his store, but that he had sent it out to a local, home based, guy. So much for factory certified care.  
 Since then I have done my own housing maintenance: After every dive I rinse the housing with fresh water and promptly dry it with a soft cloth with particular attention to the glass surfaces.  Once a year, or after a long dive trip, or after diving in sandy or murky waters, I remove one of the control levers and one control button and inspect them for rust, sand, dirt, and O ring condition. 
 If both the button and lever are clean, I continue to use the housing as is.   
 If rusty or dirty, I remove all the buttons and levers, clean and lightly lubricate them with silicone grease, and inspect the O rings for damage. Surprisingly, the O rings are remarkably long lived and resistant to damage. 
 For the past eight years my housings have continued to work as they should, with no sticky buttons or levers, and with no trip to the pro shop.

 My conclusion is one can avoid the expense, time and hassle of shipping one’s housing to the dealer for an overhaul every year or two with a small amount of prompt post-dive care and do-it-yourself maintenance. 
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 The tools needed for housing maintenance are an inexpensive mini "jeweller's" screwdriver set, a set of mini metric hex Allen wrenches, small needle nose pliers, and a tube of silicone grease. 
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Posts on Housing maintenance:

https://wetpixel.com/forums/index.php?/topic/55356-after-trip-housing-maintenance/&tab=comments#comment-359460

Optical Ocean Sales: https://www.opticaloceansales.com/files/Maintenance.pdf

Meikon Housing: https://meikon.com.hk/blogs/news/underwater-housing-maintenance

Brend Durand: Youtube  Underwater Housing Maintenance 

Mozaic UW housing:  https://www.housingcamera.com/blog/underwater-photography/the-ultimate-underwater-housing-maintenance-guide

I think it depends on the housing brand too. Until I was bored in lockdown, I’ve never serviced any of my Subal housings - all work great and look like new. But I did have a housing from another manufacturer for a short while that required 6 services.

Peter Rowlands always told me he made far more money servicing Nikonos cameras than selling them, back in the day. And was very grateful that Nikon recommended regular servicing. I suspect today’s dealers are equally grateful that the manufacturers recommend this regular income stream for them too.

Cosmetically. I also think the different finishes from the different companies age at very different rates. Despite a lot of work, my Subal housing still looks pretty much like new. Only if you look at the flash brackets on it, can appreciate its workload. I realise that most people don’t shoot as much as I do.

My housing today. Main finish looks close to new. 

But these Ultralight brackets, which are the same age as the housing, reveal the workload.

Yeah, I've a smiliar experience to Alex on a couple of points.

I'm on my 6th Subal and even after pretty heavy use, they have all looked very good. My D500 housing has done well over 700 dives and looks good as new. I'm always surprised by how worn-looking  "another popular manufacturer's black-finish housings" can be.

On servicing, I agree too that it depends a bit on the housing. Although I've never taken apart a Subal as Kraken de Mabini has, they are very easy to make small adjustments with simple tools. I'd shudder to try and tackle one of those black-finish ones.

There is an element too of "if it ain't broke, don't fix it". In 22 years of using them I've only had a Subal serviced once after a minor leak (user error, oops). It went to one of the well-known suppliers. The work looked well done but the first time I  used it, the 45-degree viewfinder fell-off as I was handing the housing up to the dive boat. You can imagine the intensity of the scream and the lunge to grab it as it descended. Maybe my fault for not checking it had been replaced security, but still......

My Nauticam housing is now 5 years old and I've not had it serviced , the housing gets a long soak after each day's diving, buttons worked then dried off- not left to dry.  A blower bulb is used to move water from recesses and even the buttons.  It looks in pretty good shape only have a few rub marks from the rough and tumble of Sydney shore diving.  I'll probably get it done in a Year or two.  Nauticam factory service is reported to have it back looking like new, though it takes a while and is pricey.

I inquired about possible service of my Nauticam Nikon housing and was advised not to bother, and unless there is a problem, Nauticam housings should be able to go several years and hundreds of dives or more without any service, with decent care.  Basically, I was told that when buttons start getting stiff, or sluggish or sticky, get it serviced.  My EM1 Nauticam housing is about 9 years old and it is fine without ever being serviced.

Of course, a lot of this would vary depending on how it is handled, on use, storage conditions, climate, etc.

I've wondered about this a lot too.   After my Nauticam D810 housing was four years old and about 200 dives, it was past the recommended service interval.   I chose to put the money I would have spent on a housing rebuild to a D850 housing instead.   The D810 rig is now up for sale.   All the buttons and levers work fine.   I fresh-water rinsed after every dive, plus a fair amount of soakings.

It's true the shiny black finish looks duller, and the white painted letters tend to wear off.  But the housing itself seems just fine and not in need of a service.

It depends. I don't think that it is easy to be prescriptive about servicing housings and number of dives/time intervals..

 Firstly though, 'O' rings do have a finite 'service' life and will potentially harden and also lose lubricant over time. Looking after a housing and thoroughy washing it after dives can certainly increase its time/dives between servicing, but eventuslly it will need to have 'O' rings replaced.

Secondly, stripping a housing and replacing 'O' rings is time consuming but perfectly possible if you are prepared to put the time and effort into doing so. That said, a competent repairer/servicer will have access to pressure testing which the rest of us don't (I used to test self serviced housings on fresh water dives but having moved I no longer can do so easily) so will service and test waterproofness. 

Worthy points, O rings and pressure tank testing.

O rings:  I have taken apart 15 year old housings, and the internal O rings were intact, flexible and water tight. I have yet to see a defective push button O ring.  The only damaged O ring I have seen is the main O ring between the housing's front and back, which one inspects every time the camera is inserted or removed.

Pressure tank testing is nice, but dunking the housing in a tank of water first for a few minutes and then overnight, to use time instead of pressure, brings out any leaks.    

I have not looked at the money involved , nor how much one saves, but in the US I suspect the shipping both ways will be about $80 to $100 and the professional work will start at some about $500, which plus sales tax, totals about $650 to $700 as a rough guess, plus the time involved in packing and going to the post office.   Instead one can inspect and do a light service in one or two hours. 

Both approaches work, and in the end, it is a matter of personal preference.