I've used the ultrasonic cleaner with a citrus based cleaner.
Like Alan said - you need to get the lube back in. I know of a console where the switches were cleaned with an aggressive degreaser and not relubed. A year or so later the switches had oxidized to hell and had to be replaced.
Here's what I've always used.
Miller Stephenson - Contact Re-Nu & lube MS-738
It cleans up your funky switches.
An SSL tech turned me onto this stuff in the 80s.
Back then it was called Contact Restore & lube.
It works wonders, and safe on plastics.
Leaves a light lube. I actually use a drop of it to lube the fader rails.
It's expensive and you have to buy directly from Miller Stephenson as in call them.
I buy it by the case, but I think minimum order was like 4 cans.
There are other versions that go under the Contact Re-Nu & lube name.
Make sure it's the MS-738
I believe the MS-738M is just an 8oz can.
The MS-739 states it is not safe for plastics, and I've never tried it.
I've used the EML contact cleaner lube as well. It was recommended by Jeff Tanner for our Neve. It bubbles up and gets into those Neve mic pre gain switch assemblies nicely. I have however never tried it on the SSL. As Alan said some of those cleaners will melt plastic and can mess up the switch latching. I have a can of LPS in the shop, but I personally wouldn't spray that stuff in an SSL switch.
