reassembly in neutral is apparently the saviour, and shimming to suit any new sift drum and forks you put in. I'm in exactly the same boat bright now, luckily i found a copper thrush washer and circlip behind one of the gears snagging and not allowing it to shift or worse GET JAMMED. Stupid $1 copper washer and circlip! Betcha no one sells just those either, will have to buy a whole new gear set. HOURS of assembly, checking, pulling apart, shimming, reassembly, checking, pulling apart 57 times hahaha.