When this happened to me i just filed away a small bit off the top of the mount and then turned the bolt out with a pair of pliers. The mount was still fine to use after.
Ye I ride moto-trials aswell as bikes just started mototrials in October and its very good. I've got a 125 gas gas 05 and am getting an 09 beta in November can't wait
orite mate r u still looking for a rear fixed hub because I have a th industries one that comes on a koxx levelboss. Very light hub comes with snail cams and bolts etc. Add me to MSN if your interested.