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The video does, but the one in the old Cobra 29 shouldn't, it has an RF sniffer with a 5pf cap sampling RF output on TX, to "turn on" TR23 that turns on the Mod lamp. Modulation positive peaks increase the voltage feeding the mod lamp, thereby brightening it. No RF, no light.
The old 29 - 23 Channel radio had the Mod light, the 29GTL and 29LTD and newer did not. It would be an easy mod to add a Mod light circuit to any radio. Just would need to figure where to mount the light. Parallel with the Meter light? Or change from bulb to LED??
You forgot to put the Emitter voltage in your original post. What are you getting there?
Broken trace at R7 (22) or Emitter of Q1 (2SC710)? Sounds like the Emitter is not being pulled down, and the Base is "following" this voltage trend. If Q1 were testing bad, you could substitute a...
When you change the jumper length, that changes the phase between the Final and the amp. This sometimes causes the amp (and Final) to go into self oscillation. Sometimes simple things like jumper length can make or break a system.
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