Adriatic is right... you need to determine exactly what is out of whack. You don't want to try to straighten the wrong thing.
Just for clarification... you said a drive wheel was wobbling, and it was soldered in place. In the pictures you posted above, is it the lower or upper set of wheels? The right lower wheel appears to be crooked, but that may not be the one you are talking about. Depending on if it is an actual drive wheel or that trailing wheelset, different techniques may need to be used to straighten it out. The wheels appear to just be diecast that are pressed in place. I can see how the hubs on the trailing wheelset could appear to be soldered, but it looks like it is part of the casting, not solder.
