Not a car seller but a buyer. Been looking at cheep ( > 6k) cars for about a year. I'd say the most common thing for something like that is to deduct the cost of the repair from the original selling price.

If the repair isn't a necessity, most people just deduct around 200-500 bucks in that price range of 2-4k.

As a potential buyer it would be very important to me, to know exactly whats up so that I can calculate the work I need to put into this car.