Gav86 are all the o rings the same size in the flow control and the cams? May as well have spares knocking around whilst ordering them.
Would you recommend having anything else for regular maintenance?
No, they are not, the cam takes different sizes for the stems, commonly available as spares…
The basic group teflon rings are all the same between groups, but there are different sizes per group, the seals on the group valves are all the same, but the cam follower pin often snaps the thread when removal is attempted, because the manufacturers, for some reason that escapes me, put thread locker on them.
The valve seals are not readily available from parts shops, they sell the whole valve, the problem with that is sometimes there is variation in length (generic E61 groups), so usually a valve from the group manufacturer works best. The follower pins can sometimes be adjusted out to make up for a short pin as the threadlock has not hardened by heat too much.
An article I did around 15 years ago.
It’s why, in my old age, I like Solenoid E61s…very little maintenance.