Unfortunately, after a quick search of the internet, I don't believe anyone makes replacement wheelsets for these locomotives.

Then the next step is to get yourself a metal NMRA gauge and a small triangular file, and turn them down yourself.

I've done this and it works well if you take your time and work slowly.

Turn the loco over and mount it solidly in a bench vise - a panovise is good, as is a bench vise that clamps to a table.

Hook the loco up to the power and crank it up to near fuil throttle. Apply the file, working slowly to file down each wheel flange to an RP -25 contour. Using an optivisor helps, and check your work often with the NMRA flange slots in the guage.

Have a hand vaccuum nearby and use it to clean up the metal filings periodically.

Once you're all done, disassemble the loco and clean out any remaining metal filings out of the mechanism.

As I said, I've done this, and it works. The main thing is to work slowly and check your progress frequently.