Unanswered Threaded Rod is not being held at its round base clamp, loses calibration. What tape(?)etc is needed

My Robo 3d R1 will not hold its calibration due to the loss of traction between the threaded rod and its round base clamp. I noticed the initial looseness and tried clamping the set screw tighter. It didn't set. Upon further investigation and attempted cleaning a small piece of crumpled cloth tape came out of the base. No doubt this original was used to improve the tolerance and traction for the threaded rod. What I would like to know are the specifics as to what that black cloth/tape is and the adhesive that was used so I can replace it myself. Over the last year of use I have oiled the threaded rod on occasion. This was probably part of the conditions that caused it to come loose over time