I'll bet the record/playback (record-bar) will need cleaning. Cleaning the heads might seem to restore but I highly suspect it's not really related to head cleaning, rather because resting the oxidized connection allows it to work again. With it unplugged, work the deck from record to play mode like 50 ~ 100 times. If the condition improves, you can probably correct the problem for a good long time by using some oxidation cleaning solvent on that switch.