[Lee] has a Hakko FR301 desoldering gun and a Duratool knockoff. He freely admits that the Hakko is probably better, but he wonders if it’s good enough to justify being four times as expensive.
If you are an electronics enthusiast who has a tendency to hoard junk because it Might Be Useful Someday, you may well have a significant experience when it comes to desoldering. Why order that ...
If neither channel is working, the problem may be in the plug or jack. Wick up the old solder with desoldering braid for a fresh, clean start. Or use a scrap piece of lamp cord to soak up the solder.