As the season slows, have a look at the riders, particularly the older rougher looking ones that look like they might be able to be made run reasonably reliably
The get them running and in season, when you get presented with a nightmare mower you can tell the customer it will probably x months as this is a big job & parts are hard to come by, I can offer you this rough running loan mower.
Thus you don't lose business taking 3 weeks to do a $ 500 repair.
Even better, nearly all of the used mowers I sell are sold this way because they find the rough mower is better than their mower.
Works really well for mowers that are missing hoods which no one ever wants to buy.
I sold 8 Victa super 24's ( 24" push mower ) in the first 2 years because the customer found that the 24" push was actually faster than their current 48" ride on + 21" Self propelled & string trimmer as it cuts 1/4" from walls and nothing stops them on 1/2 to 3/4 acre blocks.