Reply to MWB,
Is that piece of plastic (what kind?) a piece of tubing that fits over the axle and then fits into the wheel?
If so, that might work if you can secure all 3 parts together with some sort of adhesive. That's contingent on this remaining a non-powered engine to some extent as well as the adhesive.
Unfortunately my Lionel ES44ac will remain non-powered. I don't have the talent to take it to the next level