??? Recently purchased a 2002 Z440 SnoPro for daughter to race. Replaced the upper gear and chain, gear and chain remained the same size as taken out. I can not for the life of me able to get the entire package seated. Is there a trick some could please pass along. The belt is off but I can not make the upper and lower gears mesh properly. HELP this is the first of 3 sleds I need to work on. Thanx in advance.