[MrFixr55]

Reminds me of a Model 89 that I wish that I could forget, that would not playt at all, untill I measured anything, it would start.

One thing to check is the physical condition of any device such as a compensating capacitor that has an insulator such as mica. Look for cracks, dirt, grease, nicotine, 87 years of environmental pollution, etc.

Using the AM transmitter was genius on your part, glad that you were able to measure AVC voltages. If nothing else, you now know how AVC works.

Try the "Shock Test". Tap the chassis with the handle of a screwdriver. If volume changes, this confirms that there is a mechanical issue. tap more lightly and tap individual components, tapping as light as possible ill you tap the one that causes the issue.