Hey fellas I need help determining if my front diff is bad. I have my 2008 foreman trx500fm In the air with all four wheels off the ground.

When I put it in 4×4 the front wheel turns but I can stop it with my hand even if I give it gas. The is no noise at all given.

History on the bike is I bought a project that has been severely abused and swamped. right front axel is connected and left axel is disconnected(broken off)

Is there a way to tell where the problem is? At the motor? At the dif? At the axel?
Thanks in advance!