re: Anybody familiar with the early Kawasaki Brute Force?

In general they have a weak front diff, plus the design of 4x4 activation doesn’t help. The 4x4 actuator could be stuck trying to engage 4wd. I would ride on a straight path in grass or dirt and switch the 2wd/4wd back and forth a few times to see if that does it. No more than 5mph while trying this. Keep in mind it doesn’t engage/disengage instantly, it takes a few feet.