I disassembled the amp carefully, taking notes as I went. I was careful not to break off any wires in the amp. I used a can of air to clean the circuit board and the interior of the head. I vacuumed out the 1/4" of dust from the interior of the cabinet. I cleaned the cabinet and the amp panels with a damp cloth. Then I applied two coats of 303 Aerospace Protectant to the tolex and the panels.
I carefully applied two drops of 100% Deoxit to the interior of the pots and rotated then at least 20 times through their entire travel. I applied 100% Deoxit gold, with a swab, to the pins of the tubes when I replaced them.
I reassembled the amp, plug in a guitar and turned it on. It didn't work, the volume was very weak and the sound was distorted. I was bummed.
I went over my notes and discovered that I plugged in the cables from the reverb tank backwards. I reversed the cables and the amp works fine. No crackling when I turn a control and the amp is pretty. I'm all happy again.
Side note: I have never had this amp apart. The first thing that caught my eye, when I pulled the head out, is that all of the grounds are flat braided wire. I believe that is the proper way to do it.