Is that buddy L set outdoor grade? I’ve seen some eBay listings for some cheap track that I could use to expand my garden railroad.I would concur that it isn't worth trying to fix it - they sold for $25-$50. To solve most of the problems you need a completely new chassis with decent wheels and a good motor.
The Bachmann 4-6-0 is a good alternate, and lots has been written on upgrading it, etc. Alternatively, there was a similar cheap "Buddy L" loco sold for a while, and you may find one for a decent price (less than $100.)
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