SWR Workingman 15 crackling problem, repair or replace?

IME there actually aren't lot of things WD 40 is the best, or in many cases even a good answer for, particularly in the electronics product realm. I use it to loosen/clean up rusty or otherwise contaminated parts. It will act as a lubricant and rust preventative in certain simple mechanical type applications as long as high speeds or heavy load carrying of the parts is not why you picked this for a lubricant.

For me it is not the best at difficult penetrating oil jobs or at heavy duty lubrication. It will clean up tools, free up a door hinge or a lawn chair folding mechanism, remove grease or rust from something and is a jack of all trades kind of product that is best when your task is on the simple, lightweight end of the spectrum. IMO using WD 40 on/in electronic equipment is not a repair technique, it's an accident that needs to be looked at by a technician. YMMV!
 
No update on the amp yet, unfortunately. Shop has only had it since mid-October, and he did say it would be "5 to 6 weeks" before any news.

I do have a clue as to why he's so busy. He's the authorized warranty repair shop for something like a dozen different amp brands. That must keep him busy, in addition to repairs like mine.
 
Still no news. End of next week will mark 5 weeks out.

I got a 40W practice amp to use in the meantime. The headphone amp was OK, but of course the Markbass sounds better and it's more fun to play "out loud."

Decided that if the SWR can be economically repaired, great. I'll do that and probably sell it. It's too dang heavy to be a good "travel" amp, and the power (and physical size) are unnecessary for practice at home.

If it can't be fixed, then that's one problem off my plate.