What channel did you choose to peak the plate tune adjustment in the rear? Makes a big difference. Channel 20 is where the factory says to peak it. And if you spend more time below channel 1, peaking it down there would be helpful. But you'll sacrifice power above channel 20 or 30.
The fat one is the Plate Tune. The skinny screw is the Load control. The Load is set for max MODULATED power, and the Plate Tune gets repeaked next. You go back and forth until both are set to that peak.
Might be the whole problem. There are other alignment adjustments inside that will affect this, but the Tune and Load on the rear panel are where you start.
Even when all the internal adjustments are right, the radio will tend to lose carrier power below channel 1, and lose modulated swing above 40.
Usually.
73
