Well, feel bit of a cock, but...
So remember the bikes been stood since 97..
Went for a ride after changing the clutch basket (out of spare engine) and springs. Ride up the road Nd no change, except the clutch feels stronger.
Get home and stood scratching my head.. So stood still it changes fine, moving it doesn't change gear unless I lift the gear lever. Sat on the bike the lever feels stiff, get of the bike and it feels fine...
Ping, light bulb.... The foot peg moves with the lever, surely that's not right!
Turns out the foot peg is seized to the gear lever, via the bush that goes through the gear change lever. So when riding my foot is stoping the lever to return and let the gear un engage for the next gear!!!
10 minutes with heat, drift and lube and all is right with the world
Feel a tit for not spotting it earlier but it all worked when I'm stood there changing by hand.
Lesson learnt, that's what it's about