Keith sent me a possible replacement encoder for the JamMan a while back which I finally got around to checking against one of the existing parts and I believe it will work as a replacement in the JamMan. The part is:
I got an inquiry about this recently. This is my reply:
I haven't actually installed it in a JamMan yet but I checked the codes that the pins generate against a part from a JamMan or Reflex and it matches. I just did a quick google search and didn't find any parts but this is a pretty good lead. The part uses a serrated knob but otherwise looks identical.
If you have a midi rig you can also use our Enhancement ROM
to disable the encoders and set the mode via continuous controller. We also have a version of the Enhancement ROM that defaults to the encoders being disabled (JamMan has no persistent memory). You can order that here
If you always use the JamMan in the same mode, you can also just hard wire the encoder for that mode. You figure out where the wires should go by measuring the resistance between the center and side pins on the encoder. When the encoders fail, the "on" resistance goes up a little bit. Instead of being just a couple of ohms they start creeping up to the point where the part reading the signals starts seeing lows as highs or vis-versa. The nice thing about this fix is that you don't have to remove the encoder, just keep it in the target position and add little wires to the bottom of the board.
Another possible fix that I haven't yet tested is to play with the pull up/down (I forget which) resistors that are used with the encoders. The existing encoders may work with a higher resistor value. The pull up/down resistors effectively create a resistor ladder with the switch since its ON position is not quite zero ohms. Unfortunately, a resistor pack is used making it more difficult to try values. The transition value is very close though so it might even be possible to just add another apposing resistor/resistor pack to the encoder wires to nudge them up/down. There is usually one contact that is bad on the encoder so you might just check the resistance of each bit/pin and look for one with a higher ON resistance.