Quoted from tdiddy:
So I'm in the middle of a restore and ran across a bad coil. I found a replacement and it's kinda weak. I usually throw my coils in a ultrasonic cleaner, blow them out with air and let them sit for days to dry. Seeing this is the last issue before I put the playfield bacK in the cabinet. I was thinking, ultrasonic cleaner, blow it out then sit it in front of a hair dryer on high heat for 1/2 hr
That's what I do, ultrasonic cleaner, then use the air compressor with the air attachment and that seems to work great. Also replacing the coil sleeve is better than reusing the old one. Then I put the label back on with a dab of crazy glue and it's good as new.