MSD Distributor question

[Mark Brye]

Last year I had an issue where my engine, when warmed up would start to creap up about 400 RPM at idle. I did a search and found tons of information. I had found a post that mentioned that my mechanical advance springs may be to light, causing my advance to not come back to its centered position at idle. I found that puting in one heavier spring cured my problem. I noticed at that time that when I rotated the rotor, that the rotor would snap right back to center when I let go. (had two light springs after car had been dyno'd)
Now yesterday, I noticed a backfire in the engine at lower speeds. Just a pop here and there. I took the cap and rotor off because I seem to go through the MSD cap and rotors every 500 or so miles. But the cap and rotor looked good. When puting the rotor back in, I noticed that when I would rotate the rotor, it would not come back to center when I let go. I put in replacement springs of the same weight but it seems like the mechanical advance is sticking or gummed up. Maybe from all the carbon dust from the crappy MSD coils and caps I go through.
My question is, what should I use to clean the mechanical advance mechanisms? Carb cleaner? Does the distributor have to come out of the engine for cleaning? I don't want to harm the magnetic pic up by not using the correct cleaner. I hope this will fix my newly found miss in the engine.

Thanks!