I've got a 664 which is basically the same baler, just older.  One thing to look at is along the sides where the belts run, look to see if the belts have run a groove into the frame.  If the groove too deep, eventually that box frame breaks.  The frame I'm referring to is the one that holds the metal drums on the front of the baler.

If the grooves aren't too deep, you can fill them back in with the welder.  I have seen a few in at the dealership where the whole from had to be replaced because they waited until they broke.

8000 bales isn't too many.  1000 RPM is handy simply because too many tractors now days are 1000 only, rather then both 1000/540.