Clutch problem Honda NV 750 custom

[custombuilt]

Hi need help guys! My bike Honda NV 750 custom 1986 model started having problems with the clutch.
It works fine till the bike gets hot, once hot clutch dose not engage making it impossible to get it to neutral without stalling the bike or wait for traffic light! I checked fluid for air bubble its all good, no one I asked could help me about it.

[mossy1200]

Im assuming clutch set up is like the vf750f and is hydraulic pushing a rod through the casing to the clutch pack.I think that the pusher rod had a tendancy to wear and become shorter not seperating the plates and fibres once bike is warmer.