Okay, this is the main problem using yellow piston as supplied, there is a narrowing where those bands are left, right. The good news is, all three springs appear interchangeable which is what I have done instead.
I may try changing one of the white rubber rings as on one end same size.
Whilst probing inside the B1 hole out popped this springs from now where, pretty sure it popped out due to piston effect of finger being pushed in, only place is the B1 valve next door - if someone could confirm, thanks.
Does it fit in like this?
