Check the screen-blocking capacitor which couples the driver output to the PA input. A defective (intermittent) unit can cause the condition you describe.
You actually have to be transmitting with the rig and therefore generating RF power for this problem to occur, correct?
Did the problem exist with the old set of tubes?
I just replaced the final tubes and the main filter caps but i still have the noise at resonance
If so, what are the differences in them? (Manufacturer, lot #s, etc.)
The AR15/M16 - Irritating practically everyone since 1960...