Hey Jon,
Attached below is a pic I found which should represent the correct layout for the trimpots.
With your amp off, you should first exercise all your instrument's controls. Meaning, on the front of the instrument spin each pot and throw each switch like 50 times. This cleans the internals, especially needed if you they haven't moved for several years. Sometimes that can even solve a constant noise issue.
But a "microphonic pickup" could be trouble. Pickup failure is rare but does happen. If you are game, a good test is to open the electronics cavity and swap the two pickup inputs to the board - meaning plug blue to red and red to blue. Then turn on your amp and see if the problem has moved... Selector switch will operate the other way around activating the neck pickup first, then both, then the bridge pickup. If the problem is still in the "1st" position of the switch (1st off of "mute") then it points to the preamp board as the cause.
Let us know what you find. Gotta get that thing back to spec!
Jimmy J