S&S 3100/YS-25 problems

I was diving in La Paz last week with a friend who has one of the new S&S 3100 cameras with a nice YS-25(?) external strobe. The camera has few controls, one of the more "idiot-proof" new ones.

He was having many problems with it. Fooling around with it I found that both the external and internal strobes were firing, over-exposing the shots and causing mass backscatter. The only control was to turn the internal strobe off, but then the external one wouldn't fire. There was an internal flash diffuser, but it still put out too much light.

So I put a piece of electrical tape over the internal strobe and then the exposures were much better! But what a kludge for a fairly expensive system.

Does anyone have one of these, how do you rig it? How do you use the external strobe. There was absolutely no documentation with it on using the external strobe, btw.

Jack