Indeed the varicap diodes are
inside the two tuner modules ... they are shown on the schematic as VC-601, 602, 603 and 606 in the VHF tuner module and VC-501, 502 and 503 in the UHF tuner module. I have yet to open either tuner module, so have never seen them.
If your set is no longer making sound or even a hint of a picture anymore, I would suggest that something went wrong in re-assembly after the batteries were installed... it is
very easy to mis-align the Berg pin connectors, usually with disastrous results.
jr