Anyone know O-ring sizes for Buttons / Dials on Olympus Housings

Hi
I have a Olympus E-620 and PTO-E06 but i am sure this post would refer to many Olympus housings

About time i serviced and replaced the O-rings on some buttons and Dials in my Olympus Housing , but does anyone know what size they are or how to Identify them , I have Olympus part Number and a Part Name but the O-ring ID i cannot work out EG O2.8 or another O2.5 or O6.07 or O3.8 or O4.5 or 110.72 or 11.5 or S3 or 17 , etc etc

I would imagine they are a Japanese JIS B 2401 but these numbers on the Parts list aren't there or even similar .
Does anyone have any ideas Maybe a Different Housing as i am sure many use the same o-rings .

have hopefully attached a Diagram and part Numbers

So if anyone has any idea of the O-ring sizes would be appriciated
Thanks Mark

PT-E06 Exploded Picture.pdf