Very unlikely that missing C410, Loss of some VCC decoupling would be the problem.??
I would lift just one of the T401 secondary leads and run the plots.??
But first I would double check all solder joints under high magnification.? Should result in a gain reduction compared with normal operation and probably screw up the Diagnostic/Audio Freq Sweep.
Another debug test would be to Lift the T401 Primary and connect it to the <RXIN> that can be accessed at the intersection of C402, C402, C494 ( this could also be found as one side of C403 which is not installed)? This would bypass the BFP filters and? the plots?should be higher gain without much filtering.
I am pleaded to help.
Chris
