Heathkit HW-101
Erratic/Jittery LMO Tuning
Fix

My HW-101 had erratic LMO tuning and would drift quite a bit even after a 30 minute warm up period. I tried the Heathkit Service Bulletins that pertained to HW-101 LMO drift and erratic tuning but the recommended actions did not cure the problem.  I even considered the problem could be caused by aging Jackson drives. That too was found to be not true.
The LMO's variable capacitor has a very thin flexible shaft to frame connection on both ends of the capacitor's shaft. I use DeoXit D5 contact cleaner, applied with a cotton swab, and worked/adjusted the variable capacitor thoroughly 3 to 4 times. I powered the LMO from a separate  150VDC supply and a scope connected to the LMO's output. The cleaning helped but the problem returned within a short period of time, less than a month.
I read a few comments on qrz.com forum where some members corrected this problem by soldering a wire/braid from the capacitor's frame to the capacitor's shaft. Even though this cured "their" problem, I didn't want to go to such extremes with my HW-101 LMO variable capacitor.
The fix I ultimately found was to thoroughly remove all the old capacitor bearing grease from the LMOs variable capacitor then apply DeoXit L260Ap conductive grease to thoroughly coat the capacitor bearings. Work the LMO variable capacitor throughout it's rotate range a number of times while watching the bearing end. The grease should not work its way out of the bearings, the grease should remain coating the bearings. Doing this eliminated not only the erratic/jittery LMO tuning but LMO drift also was significantly reduced to less than 100hz within the first 30 minutes of warm up. I installed the LMO back into the HW-101 and allowed the HW-101 to warm up for 30 minutes. I worked a few stations on CW, each being told I was using an HW-101. One of the stations reported “your HW-101 is stable as a rock" and that was after 30 minute warm up and a 20 minute chat at full power (95 watts output).
I performed the above procedure to my Heathkit SB-303 LMO which had the same reoccurring problem, erratic/jittery LMO tuning and drift in the LMO. The same positive results were achieved.
If you use DeoXit L260Ap conductibe grease, ensure you read and adhere to the warnings on the side of the container!!!
Another possible source of HW-101 LMO drift is a bad/gassy 6AU6/6AU6A LMO Buffer/Amp. The tube can be checked by substituting the LMO 6AU6/6AU6A with the 6AU6/6AU6a in V3. Swap the tubes and power up the HW-101. Connect a 11meg analog VTVM to pin 1 of V3. Pin 1 grid voltage should always remain “negative”, NEVER positive. If, after 3 to 4 minutes, the grid voltage on pin 1 of V3 becomes positive then that indicates a gassy 6AU6/6AU6A and that tube should be replaced. A gassy V3 6AU6/6AU6A will also cause the S meter to drop below zero and quite often the Zero pot will not bring the meter back up to zero.

73
Mike W5RKL