Zenith 2 Stripped Knob
Challenging to view from lack of light, but this image shows the perspective from looking down the interior of the Carrier, that the end of the tube should be round.
This is the same view with illumination. Note the accumulated debris from the wear in the bearing. While unsightly and should be cleaned, this is considered normal in a table that is 26 years old
After cleaning the interior of the Carrier a little bonus was found. There was stripped threads from the original brass stud.
A little out of focus but the bore is now clean and round.
The Carrier was repaired by way of a thread insert, the stud in the Knob was replaced with a brass stud. When asked about a warranty on the repair, the customer was assured the table would fall down around the repair i.e., warrantied for life.