Well I am not familiar with your coach, but the key items you mentioned were: you have power to the generator (do you mean there is 12VDC somewhere on the generator like on the started solenoid?......and “it does not crank”.
If the starter motor does not crank you need to find out why. Generators start off coach batteries so check the typical 100 Amp breaker (normally mounted somewhere neear the coach batteries on many coaches) is not tripped.
Can you crank it from the start switch on the generator if the one in the coach does not work? Carefully check for clean tight electrical connections on all the starter electrical path connections (i.e., bad ground connection etc). Maybe just a bad starter motor?
__________________
|