How to clean switch on Vintage 70's Board

[sodderboy]

They designed that cool chamfer on the nut to funnel surface debris into the switch.
Spraying under pressure redirects back into your face. It’s a “sealed” switch.
I would try on one module: a lube-less electronic cleaner, contact renu (CR) for reference, dripped by hypo needle into upright switches until filled, let sit, exercise the switch 20 or so times, turn upside down to slowly drain into paper towel. Now spray a shot in it while upside-down, and let sit for 10 minutes. Spray with compressed air (oil-filtered if house air), and apply a drop or two of Caig ProGold in the upright switch. Test audio back in the console.
The issue with cleaning a sealed switch is that there is dirt, lube, and oxidized contacts inside. Just power-washing it liquifies all the stuff inside and it then settles into the contacts. You want to liquify it, remove it, then re-condition.
This would be only a stop-gap solution. On an active console I would replace the switches.
Mike

 

[transient]

Spraying under pressure redirects back into your face. It’s a “sealed” switch.
I would try on one module: a lube-less electronic cleaner, contact renu (CR) for reference, dripped by hypo needle into upright switches until filled, let sit, exercise the switch 20 or so times, turn upside down to slowly drain into paper towel.

The C&K 7000 Series switch is not hermetically sealed, hence my suggestion to press down on the lever as this opens a small gap around the lever which will admit your chosen contact treatment. Certainly drip (or flow) rather than spray! My approach would use the 'stop gap solution' to get the entire signal path working and then assess which elements need detailed attention.