I noticed an interesting thread on the US board.

Billman suggested sandblasting the worm gear to replace the friction found in a new TCT.

It seems the worm gear gets polished with use and it is this that causes the the TCT's failure as it fails to tension the chain when it slips.

A few of them have taken it out, sandblasted it to get rid of the polished areas and it has cured the problem, whether it lasts is another issue.



Full thread here:
TCT replacement

 

used sand paper, seemed to work. no more m1.