Ok so a few months ago i was riding along going pretty fast and my piston shattered, seizing the motor whick locked up the tire and caused me to come to a skidding halt. i took it to the shop and they rebuilt the whole motor doing a top end and rebuiling the crank. when i got the motor back(i took it out of the bike myself) it was stuck in first gear, if you held up the shifter and rolled the bike forward it would go into neutral but not second. i took it back to the shop and they cant figure out what is wrong. they said that the cases look fine no cracking or warping the shift forks are all good the shift barrel is good and they also checked the gear stacks and said that all the gears are fine. what else could it be? did i break something when the motor siezed or is the shop just putting it together wrong? they have had it for almost three months and i am getting impatient and want my bike back so any help would be much appreciated.