Tumbler Flat line start

When engraving tumblers, the first couple passes on 50w omtech are flat. It is not noticeable on many projects. Small letters and circles are the most visible. My rotary is a Mansfield Customs. After the initial lines everything is perfect. Any ideas what is causing this? Or how to fix it? Thank you for your time.

Judging from the picture of the roller, the setscrew holding the pulley to the motor shaft is loose. The motion to the start of the engraving shoves the pulley to one end of the backlash and the backlash unwinds during the first few engraving passes.

While you have the hex wrench out, check all the other pulleys where backlash can hide. You want the setscrews firmly tightened on the middle of the flat in the shaft.

Looks like a nice rotary and it should work fine when you get things snugged properly.

I will check that out tonight and report back. Thank you very much for your help good sir.