So, I replaced all four belts in my tape deck, but that still didn’t solve the problem with the left player. While I was installing the belts, I found a round magnet stuck to the inside of the cassette player’s frame. I wasn’t sure if it served a purpose where it was, but it looked out of place.

I looked at the other tape player, and it didn’t have a magnet in that spot. It had a similar-looking magnet on a plastic gear with a little sensor mounted above it, so I stuck it in the same spot on the left player, but it had no effect. I went inside to do some research and found a video where a guy had the exact same problem. He glued his magnet in place, and it fixed the problem.

I went back out to the garage and epoxied the magnet in place, but it still didn’t work. Then, it occurred to me that magnets are directional, so I stuck a dental pick to the visible face of the magnet on the right tape player, and it stuck. Then, I tried the left player and it didn’t stick, so I knew I had glued the magnet upside down.

I frantically took the player apart again before the epoxy could set up anymore. I cleaned both surfaces with alcohol and put the player back together, but in the process, I broke the wires from the circuit board to the motor, so I had to solder them back in place.

Once all that was done, I put everything back together, tested both players, and they both worked perfectly! Since I had the whole thing taken apart, I looked around to see if there were any other obvious problems and noticed a bad capacitor, so I ordered a new one (10 actually), and I’ll install it tomorrow. I feel accomplished!