My buddy just bought a 00 KX 250 in need of fixing. It is missing the clutch cover/water pump /kick starter and gear. I went and bought a manual for the bike.

I started looking around and noticed that the casing behind the kick starter gear has a hole clear through the casing. I looked it up in the book and it shows the casing has a slot for the gear to sit into. I called and got a new right-side casing and all the covers including waterpump.. The guy i talked to said something must be wrong with the tranny for that to happen. I called and spoke to the previous owner, he claims the bike was dumped and the casing cracked. Would what you see happen from dumping the bike or is that bs? I took everything apart, cleaned and put back together. I can spin the shafts and the sprocket turns. The motor has plenty of compression.

What should i be looking for if something is broke?