More or less think of it as a way to rearrange your i/p's and o/p's via a bay of wires much like the way telephone operators did back in the day. Yes, you can also have a patchbay for time based and dynamic effects as well as signal routing throughout your theatre. They are also used in broadcast trucks to route audio and comms which.. ive seen and they are ridiculous sometimes taking up whole walls. The question about the brass connector i would have to say just leave it and work with cleaning the mechanical way that i stated. ADC a manufacturerelajdla however u spell it w/o being corrected by some smartass hs kid makes patchbays and they suggest not to use any cleaning solution b/c it can damage cables and make them short or just not conduct over time.
hope this answers
hope this answers