hi all, anyone know the cause of this?? and easy fix?
There is a short stack of springs and arms under the transmission cover, that engage the shift drum and are held in place by a nut. If that nut is loose, weird things happen.
If not, its nearly always a bent shift fork with attendant wear in the groove of the gear it engages. Requires engine removal, flip it over and take bottom crankcase off to service the trans.
Review those thread links that were offered to you.