Just put the engine back in the frame after some much needed cleaning, and the kick start wont turn over.

I dint touch the engine internals apart from taking the clutch cover off to check the clutch plates, and it was working fine before.

Any suggestions before I undoubtedly have to undo my handy work of liquid gaskets!

Cheers, Joe

i would say the return spring for the kick start has slipped, so there is no tension to engage the ratchet. remove the side casing and just check, you may need to remove the clutch though to replace it.