OHV clutch bleeding issues , with an answer

[Triumph1300]

Ok, I've been swearing at the Toledo this afternoon, with the usual soggy, will it, won't it disengage clutch.

It seemed to bleed ok with a vacuum bleeder, but no pedal.
Bled ok with conventional means, but still no pedal.

We suddenly realised, that the master cylinder piston wasn't returning fully, Only by a few millimetres, but enough to stop things working properly.

It was temporarily cured by the use if a hammer, and penetrating fluid, as stripping the cylinder wasn't an option this afternoon.
Worth checking if you are having issues.