RCI 2970 N4 Suddenly Lost Around 1/2 Power or more

[Wire Weasel]

Hi guys, Could use some pointers. Rig uses 4 pills, likely 2290 equivalents. Examined RF Deck. Heated rig up with 50W keydown. All 4 pills heating up about the same checked with infrared thermometer.
Normal: AM will key 150W swing to 400. SSB/400 (did not run wide open ever - usually key at 80 or 100 to talk)
Now: AM to 110W swing to 175. SSB 110W
.
What might be the problem? I am not a tech but do have some electronics skills. Can solder well and have an excellent VOM. Please throw me lots of details and pointers that might assist me in the diagnosis and repair if you would. A knowledgeable local has suggested the AM Regulator may have partially failed?
Thanks for any help !!

 

[Eldorado828]

If it were me, I'd start by turning off the 4 pill amplifier section to troubleshoot the radio alone first. The plug near the finals by where the mirror board is located is how you can disable the amplifier section. There's a thread around here somewhere that shows that part.

Once you can rule out the radio itself then move on to the amp section

 

[Wire Weasel]

Yes. If say the AM Regulator is bad - that's in the radio section, which is a 2950. However, it comes power-tuned to run the amp rather than as a stand alone 2950. So I also don't know what the factory settings are on it as is - to tell whether or not I'm seeing correct readings. I've had one of these before several years ago and the amp section went bad so I disconnected it and retuned the radio to operate as a 2950. I remember that the AM Low & Hi settings were turned down much lower - so I adjusted both to be 1W Low and 10W High.