fixing a drive axle limp????

i got an EF65 off a local website the other week. it has a pretty bad limp in the drive axle.
rather annoying since its one i cant just go buy another of. theres a few on jauce, but i dont want to spend more money for no real reason.

ive stripped and cleaned it, and cant see whats causing the limp.

next trick will be swapping the tyres, not sure if thatll help, but worth a try.

any other advice or ideas? normally i would swap the axle, but it has yellow wheels, and i dont have a spare set that color, of course.

[Super]

My only idea would be to completely remove the wheels and axle from the train and roll it on a flat surface. You may be able to see what it is. Also the hole in one of the wheels may be a tad bit off center which could cause a limp from the manufacturer.

thanks, super. ive got it here now so will do another tear down. good idea about the hole being off, wouldnt have thought of that. its quite pronounced and even a friends 3 year old son said it was wobbly, lol.

ok, just stripped it again and managed to remove one wheel. it appears to be an issue with just this wheel, as it doesnt roll true. hmmm, thinking cap time! it feels smooth enough, but im also seeing that the limp happens in one spot only, where it looks a little squared off. will try a new pair of tyres, they might be fat enough to pad it?
found my tweezers have a kind of file/rasp pattern on the handle. that was enough to smooth out the bad spot, and its eased the limp from what i can tell. its still wobbling a bit, but nothing like what it was.