I have a Shockwave that I have only played with a couple of times and the wheels wobble. The rear right so much so it rubs the arm and upper link thing. I took it all apart and believe the brass bushings have worn out. Is this considered normal wear? I'm almost sure it's the bushings. I'm going to try a local fastener shop to see if I can match them, I hate to think I have to order them that often. Is there some type of automotive grease that would prolong life? Are there bearings available?