2001 foreman 500 rubicon grinding noise
 

hi guys, I am working on a Rubicon 500 for my dad. here is what is going on.
last year he was driving it and all at once lost all forward motion.( on flat ground) when starting the bike it would fire right up go into gear give it gas it acted like it wanted to move but then would make a grinding type ratcheting sound, and not move. So here's' what we did: pulled the motor, changed the oil pump, sprocket, and chain. (chain was stretched). got it put back together, now it moves in both forward and reverse, but makes a different grinding noise. I guess I should note that while taking the engine apart we broke the angle sensor. put a new angle senor on it. I tried to perform the start up procedure for after changing the angle sensor, but I'm sure that I screwed up the procedure. would that cause the electric shift motor to make a grinding sound if you don't have the angle sensor in correctly (procedure wise)? also I should mention I don't have the oil filled all the way up yet dad only bought a gallon (4 qt.) requires 5.2 qt. would that make a difference? planning on filling the oil up the rest of the way and see what happens. my manual is not very clear on how to make sure the angle sensor, shift linkage, and electric shift motor are all in sync. or is this all normal for start up after you have this machine apart. this bike is complicated makes me appreciate the simplicity of my Kawasaki bayou's
thanks
Joe