Static, left channel from B&K EX-4420

Is it possible that it is related to something as simple as a slo blow fuse?

Otherwise, is it worth repairing. I paid $400 a few years ago for it. 



Definitely worth repairing. they were built between 1993-1998, so they're 25+ years old; may require some maintenance.  

hi, re: Output relay; Thanks for the suggestion- can you point me in the right direction for where I might find one? Thx, Frank