After buying my TL 18 I had problems with my encoders over a couple of years, causing skipped stitches from the needle staying up or down, though I didnt know why at the time, and no acknowledgement of a problem from the dealer. Then I found there was not enough weight in the encoders, so they barely touched the tracks in places [ lots of places], preventing the regulater from working. I managed to squeeze bits of styrofoam between the encoders and under-carriage to put pressure on them, and havent' had any trouble since. You may have a handy hubby who can figure a better way to weigh them down more. Good luck & let us know how you get on.
Cheers