My LGS used to save troublesome low-end launchers for me. He would give them a onetime test to see if they would work then they went to me. He said they were just not worth his time to fix.
I find them fun to putz with. Most just need a good cleaning,,,,, Seems most low-end gun buyers are not familiar with maintenance.
Go figure.
When I got a few lined out and tidied up I would take then into a local Pawn Shop ( good to have a paper trail on them) and swap them for something I did want.
Pawn Shops have a market and LOVE to get cheap guns.