Traction Issues with Old Style Plarail James

Yes, his wheels keep spinning on the curves and his traction tires are in pretty good condition, and centered properly on the wheels. I've given the AA battery trick a try and while he goes considerably faster, he still gets stuck. I'm not too keen to open him up given how rare the old style of Plarail James is but if you guys don't have any other ideas I might just have to give it a try.