I've run in to a problem like this before, I should log these things down, I would check out your oscillator circuit., I believe that was my problem , those IF transformers in the 50's GM sets are not my favorite, you can get in to trouble trying align those slugs ,I've seen IF's short between the primary and secondary the only way to find it is voltage check ,high voltage on secondary, I've got around 20 parts sets for that radio, you might want to isolate a suspected problem parts and jump in a know good one , the problem is that the old service info does not take in the fact the radios are now 50+ years old, keep at it I've repaired some fairly bad radios before
