This time it's a bumper mainspring question. Maybe need a new mainspring for this Tissot watch . Slipping and low amplitud. Checked cousinsuk and they have a non-automatic mainspring for this caliber. But as it's a bumper shouldn't it be a automatic mainspring?  For the 31.21 they say automatic.  http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Tissot_31_1 http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&0&2uswk&Tissot_31_21