Fast-wearing OEM chain and sprockets
Owners widely report the budget factory chain stretching fast — constant adjustment, then replacement by 10-15k miles, sooner when lubing was neglected. Spin the rear wheel and feel for tight spots, look for hooked or shark-finned sprocket teeth, and pull the chain away from the rear of the sprocket — visible daylight means a full chain-and-sprockets kit is due.
Ask for repair records covering this item. If it hasn't been addressed and the car is in or near the mileage window, price the $250–$450 repair into your offer — or make it the seller's problem.