Force .15 2 speed transmission not changing back

[uggish]

I have a GV BV1 with a 2 speed transmission in it, but im having trouble getting it to change back quick enough, it seem to get stuck in 2nd, i race on a small track a couple of 30M straights and a hairpin and sweeper, i can adjust when it changes from first to second, but it seem to make no difference when it come out of a corner still in second, it idles ok not too fast that you would think its getting stuck on rev's.
im about to turf the 2 speed any ideas ?

[truckzilla355]

Maybe pull it down, im just guessing but if the throw out shoes have a indent where they contact the pin for 2nd they may not b able to slid off when the revs drop. A light file to make the end flat again might work.