Unfortunately, my rubber hose hack from Part 2 worked only for a few weeks. The belt again stretched, and became loose:
One thing you can also see in the photo above is that I’ve slid the motor as far to the left as the adjusters allow (the slotted holes for the two brass screws). I couldn’t bend the motor mounts any more to tighten up the belt, so in addition to the rubber hose shim from Part 2, I wrapped 4 layers of electrical tape around each of the two pulleys:
Amazingly, this increased the diameter of the pulleys enough that the belt became taut. I have tested the chair for a few hours, and this fix seems to be working well. Let’s see how long this hack holds up…
Previous related article: How to Repair a Panasonic Massage Chair, Part 2