Smith-Corona Series 5 and 6 typewriters had a small piece of rubber around a portion of the escapement which can wear out or become damaged. This in turn causes the escapement to not work properly and cause the dogs to get jammed resulting in large movements of the carriage while typing or spacing.

Joe Van Cleave calls it the "return silencer" and replaced his by tracing out the damaged piece on a sheet of 1/32" rubber and cutting it out as a replacement.

Duane at Phoenix typewriter describes replacing it with rubber tubing (possibly something like heat shrink?) instead. See: https://hypothes.is/a/tG4BWk77Ee-jczsjoM8SzA

Typewriter Escapement Repair by [[Joe Van Cleave]]

Smith Corona Typewriter Repaired Flying Carriage ! Fixed Escapement Pawl by [[Phoenix Typewriter]]

Pawl was frozen on escapement. He also took out a piece of the rubber which he planned to replace with some surgical tubing to add a small layer of spacing.

This repair is similar to part of that at Smith Corona Typewriter Power Spacer Escapement Repair Adjustment No Silencer Model

Smith Corona Typewriter Power Spacer Escapement Repair Adjustment No Silencer Model by [[Phoenix Typewriter]]

SCM typewriter escapement and margin lock/release by [[Nis Kildegaard]]