Thanks for the advice. I am looking at this unit to buy, so replacing parts first is not really an option. I will, however, check the three things you mention as an easy fix, but may have to take a gamble.
When you talk about the wheel hubs, I have never seen them apart so what is it should look for? Do I need to jack the tire up and see if there is play rotating back and forth? If so what does this indicate?