Y Axis Shift on Modified Taz 1

I have a Taz 1 that has been upgraded to the Dual Extruders and along with the other hardware, I am told in essence it is a Taz 4. I just started to experience some Y Axis Shift. The part I printed yesterday was fine. Today I multiplied am printed 5 of them and I am getting it to drift forward. It is about 2 cm off about 3 mm up on this series of prints.

This is the first time I have experienced drift. I am printing only in one color with other head turned off in ABS at standard quality.

Thanks for any advice.

Henry

That’s either a loose belt, a loose motor pulley setscrew, or anot electrical issues. Usually it’s the setscrew or the belt. It could also be axis binding or a gummed up bearing on an older printer.