print registration on a mimaki jv3-160sp

[jwisequalitysign]

any help or suggestions greatly appreciated. about 42" into the print it begins to look like this (picture posted) for about 2.5" then corrects itself.

 

[J Hill Designs]

dirty encoder strip is a possibility

 

[jwisequalitysign]

Thank you, had to figure out what the encoder strip was and the find where it was and how to clean it but you got me on the right path thanks.