I would check for any possible "cold" solder connections, especially where you have replaced the capacitors. They should be very shiney and not dull. If they are dull then they are cold and need to be resoldered. If you have a schematic and parts list make sure the replacement caps are soldered to the correct terminals. I myself have had to correct my work from time to time due to the latter.
Bob WB5YYX
:I replaced the caps in a Silvertone 6421 and now all I get is a hum. I jigglled the first cap wire with the radio on (is this stupid) and it seemed to clear up a bit.
:
: