Encoder strip or sensor?

May be the lens that reads the encoder strip.

 

What did you clean the encoder with? If you used anything less than 93% alcohol, the encoder strip is probably damaged. The encoder strip is made of graphics film, processed in water based chemistry. Lower grades of alcohol contain more water than higher grades and will soften the emulsion of the encoder and if you are repeatedly cleaning it in very brief time, you can damage the emulsion.

I actually do not recommend alcohol as a encoder strip cleaner, but use acetone and a high quality microfiber cloth instead. The acetone will not affect the encoder strip in any way, and is much better at removing ink residue. Wear plastic gloves. Wet a light colored microfiber cloth generously with the acetone, fold it over both side of the strip, pressing fairly firmly, and pull the strip through. Do this repeatedly until either there is no more ink showing on the cloth or it squeaks as you pull it through your fingers.

I have cleaned over a hundred encoder strips this way and have never damaged a single one. FYI, another sign of a dirty encoder is if your prints start shifting in one direction while printing.

Regards,
Jim

 

The screw being stripped could sure be an issue if the sensor is not firmly mounted. The sensor is just as important as the strip. I have had the sensor turn just enough to rub the strip and damage it. Good luck.