DON'T try to turn the wheels. See what Richard ^^ said. The drive wheels on Lionel's 700-series Hudsons can sometimes be turned by hand after a LOT of break-in running. I wouldn't try to do it on a mint or low-mileage example, especially one from the '90s which are known to be 'tight.'
If you take the shell off, you could try to turn the drive shaft where it emerges from the motor. If it turns freely, you're in good shape (at least mechanically.) It would still be prudent to put a drop of oil on the motor wick, axle bearings, and after a few minutes of break-in running, on the side rods.
