HP Designjet Printers - Cleaning the Encoder Strip
Time Required. This guide will replace the encoder strip, which the printer carriage uses to read its speed and position. It runs through the opening of the carriage and is attached to each end of the frame inside the printer. Without this strip, the carriage will slam against the side of the printer when it is turned on. Buy these tools.
What is the problem you are having with the encoder strip? If the printer is skipping an area in the same spot down the page, stairstepping text down the page or slamming into the side of the printer you might try cleaning the encoder strip as shown in the post here. The encoder strip is fragile, please read and heed the warnings.