How bad is this?

First get a small vacuum they use on computers , the if that works stabilant 22
put on the pot ,I have had a similar problem with dust and this is a super conductor protectant and fixed many a oxidized component well worth trying and the stabilant 22 Is great for all low powered items like rca,speaker terminals used by hundreds of high tech 
companies for years and makes everything sound a bit better once cleaned including vacuum tube pins and protects if not moved for a minimum of 12 years
if this works I would put some electrical tape around the exposed area to seal 
it if possible.  If you have to replace it buy a better one like a Khozmo attenuator
they use a resistor ladder and only 2 resistors on the output and is sealed
about $400 with  nice remote if you have to do a repair make it better with a few mods. 

I have a recurring problem with my system:  The right channel plays hardly at all now.  I switched the cables between the pre-amp and amp, and the problem remains on the right speaker.  That would seem to indicate there is a problem with the connection to that right speaker, rather than with the right channel in the pre-amp or amp . . right?  But I checked the right speaker cable and the connections are secure.  And these are passive speakers, so there isn’t a amp in the speaker to go bad.  I’m stumped.

I got my problem fixed, again.  There must be a problem with the right speaker connect on my Parasound A21.  I checked and switched various speaker connections and finally got both speakers playing fine now.  I have checked connections before and the problem remained.  Don’t know quite what I need to do to permanently correct this, but I am glad the problem is not in the amp or pre-amp.