Stuck switch on Pultec Filter

[aprats]

Long time lurker, first time poster. Really appreciate the help you’ve all provided over the years!

I recently picked up a stereo Pultec filter, HLF-23C, which is essentially two HLF-3C’s in a single box. 3 of the 4 centralab switches turn beautifully. One is completely jammed / stuck. Any wisdom to share on the best way to get that switch moving again?

 

[gyraf]

..most often grease around shaft bushing has hardened and is stuck. If metal shaft, take off knob, heat the shaft a bit with solder iron, get it turning with pliers. Keep moving while cooling down. Perhaps try to flow a bit of oil in there..

 

[aprats]

Thank you, Jakob.

Following up on this thread, I tried heating the shaft and turning with pliers, but the stubborn switch wouldn't budge. A little protected spritz of non-chlorinated brake cleaner did the trick. I then flowed in some oil and now all the switches are buttery smooth.

Spent the past couple days giving this guy a good scrub down and now it's ready for action.