I just tried using my Dremel with brass cone wheels. Couldn't find any Dremel brand ones, so I bought a set from Harbor Freight. Talk about chinese quality...the spinning cones immediately flatten out into a plate shape, then pieces of brass wire start shooting out, good thing I had on goggles because I could feel them hitting my face. I was able to clean off the contacts before the first cone self destructed, but couldn't get in underneath where there is still some of the blue green stuff. Next will be to try the CRC Battery cleaner.
I couldn't wait, so I put in eight new AA batteries, turned on the HX1500...it immediately start scanning through some settings I put in 15-20 years ago. What a radio, sounded like it was brand new.
I have a collapsible/extendable (about 36") antenna on it. Is there a critical length, or is it just the longer the better?
Lots of good suggestions, and no one has said that the blue-green stuff won't come off...so I'll keep trying to get down into the cracks until I get it all.
John