Deoxit on the power switch won't hold for long, the contacts are shot and will continue arcing.:sigh:
If you have the power switch associated with the speaker selector, you may be able to fix it, as this switch is easily opened up and closed again.
The switch may look about the size of a book of matches, mounted at the rear of the speaker selector shaft with two tabs with wires at the top or bottom.
Unplug the set from the AC line, and remove the two small nuts holding the switch in position, and slide the switch backward off the shaft and the two threaded rods, noting the position of a small rotating "cam" that fits in the center.
The switch comes in two parts, a front and back, open this assembly and see two brass strips with small buttons at each end (these buttons will be blackened and rough).
Gently polish these buttons until shiny using a fine grit sandpaper, blow away the dust.
Slightly bend the brass strips so the contacts (buttons) have firmer contact with each other and re assemble them into the slots in the plastic case you took apart previously.
Re-install the "cam" that opens the switch when you dial "off" on the speaker\power switch.
The easiest way to do this is to place the cam in place with the switch "on", set the front panel knob to the first "on" position and assemble the switch cover and place back on the shaft\threaded rods and test briefly to see if you got the position of the parts correctly (safest way to do this is with the "continuity" test on your DMM).
Once the switch is making\breaking the circuit properly, put the nuts back on the threaded rods and tighten snugly but not too tight.
Other switch types might be "rescue-able" using a similar technique.
Mark T.
