First thing first;
Did you take the wheels off for repair? If so You have lost whats known as the drive key. It is a squair metal bar that sits in a slot both in the wheel and the axel. Thats what causes the wheels to turn. Look and see if there isn't a slot in the hub where the wheel meets the axil. Let me know what you find.
Lester (chetsbro1@cs.com), August 2004