it's pretty much been said, but looking at the power supply board in the bottom of the cabinet, the fuse holder for F1 and F5 are tarnished/oxidised.
i'd be replacing them, it's a tedious job on that power supply, but start from the mains coming in and work your way along.
not necessary but the power supply board is dirty and will come up a treat with a wash, if you go as far as removing it.
maybe replace the bridges? not necessary if you have correct voltages, it's just what i'd do.
i know you haven't asked, just a suggestion...raise the board
also check all solder joins for dry dry joints, or if in doubt, reflow all.
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