I have an old Minerva machine with external motor recently had a few shocks from metal so husband replaced the motor with one I had from another machine which was used very little....No more shocks but sews backwards ...any idea why...its a basic machine with slider for stitches 1 to 4 and up for backwards ...now does backwards and forward only when in the up or backwards position so I have no control over length of stitch....

Pollytunnel, December 2011

This may soon stupid because i am not familiar with model but did you check the rotation off the motor you took off? lot off machines and overlocker work with clockwise rotating motor,suggest you check this first before sending machine to set balance.

johan, December 2011