Scuba, Phil, Carlos... many thanks for the input. It is appreciated.

I doubt the piston seal has had a chance to bed in yet and it was pretty snug on reassembly. The spring is HW from the TBT kit and I have read on here that the old 77s had quite a bit of preload as standard? And yes, I mean how much spring is on show before the trigger block goes back on.

Should I remove a coil or two then at the risk of having to get another spring if it makes things worse?

Adding or removing both the power washers made little difference either way.

Thanks again,

Darren