Sun Roof 87 300D

[dkw]

Suddenly, out of the blue, the sunroof has irregularly began to stop about 2/3 open, and not respond to the switch.
After slight movement of the hex drive in the trunk, the roof will complete its retraction.

When closing the roof, the first 1/3 or so moves as expected, then will "load down" some, and sometimes stop, leaving the roof 2/3 or so open. Then may (but not reliably) close.

Does anyone recognize this as a symptom requiring lubrication?

Is there some proceedure to lubricate the mechanism?

Is the motor replacement, if necessary, a task a shade tree guy can tackle successfully?