Hard To Change Gear When Stopped

Unknown

28 Essex - When stopped it is hard to get to change (move the gear lever) from current gear to next i.e. from reverse to 1 st. If the engine is stopped the gear change immediately becomes easy. The gears are still turning so there is mild grinding so something is binding. (It has a non cork clutch which has been good).

I have adjusted the clutch so there is plenty of travel to floor for release. Changed the clutch fluid (Dex 3 ATF to correct level),

This hard to release problem has been an issue since working on gearbox and clutch a while ago. It seems to be worse when cold.

I found mention of the correct thickness of clutch assy gasket being important by Alistair H. - what should it be as I would have replaced the old one?

Could it be the spigot bearing which was replaced or the clutch yoke not putting even pressure on both sides when pressed?

Any clues from others previous experience would be appreciated before I pull the gear box out. 

Cheers, Peter