M-300 slurring issue

[JHM]

Our Harris m-300 recently had the main drive motor replaced and sense then we've had major slurring issues. Some times it's all the units most time's it's either the black or Yellow. We replaced the infeed harmonic which seemed to help for half a shift but now it's slurring again. Our maintenance staff is convinced the slur is caused by the infeed because the temp fix the harmonic made but I'm not so sure. Any idea's to help pin point our problem would be great.
There is a bounce threw the hole press you can see the color dots really moving around on the CCR monitor, our (gmi) auto color system isn't picking up the color bars correctly also having issues with our compensation holding steady.
Thanks Jeff

 

[Tlang]

Double check belt tension on motor