I have been messing about with an ultrasonic cleaner recently. They have many uses from cleaning jewelry to removing rust.
Today I took a Bengall with rust spots, some pitting on the spine and quite a mess in the pivot area. I watched as the filth n rust came out from the pivot area. The blade came out tarnished but that was a light coating which the buffer easily removed to reveal a sparkling blade. The pivot area is completely cleaned out.
The Machine.
Attachment 310863
After 15 mins in special solution. (sorry no before pictures)
Attachment 310864
After a quick polish.
Attachment 310865
A clean pivot area.
Attachment 310866