With time, the encoder o'rings can become brittle, checked or cracked such that they don't roll smoothly or evenly with machine/carriage travel. Encoder o'rings are located on the encoder wheel, one on the side machine stitch regulation encoder and the other on the carriage stitch regulation encoder (either traveling on top of the back frame rail, or riding inside the back rail). It is recommended to replace the encoder o'rings every 2-3 years.
Installation instructions are found in "Basics & Beyond with Nolting."
