The button on the controller on my 503 is very hard to push. I've read Archaicarcane's blog post on it. I've also watched several videos on taking them apart and cleaning the contacts and adjusting them. One completely disassembles the thing and cleans everything except the ceramic tube with degreaser.
I left the 503 (has a 3 wire plug similar to 600 series) at school, so I can't really test it. However, the measurements archaicarcane gives indicates my controller is is in adjustment. No one mentions any lubricant being used anywhere.
I'm going to take it apart and clean it and hopefully get it back to good adjustment without testing it.
Any suggestions as to how I make the button easier to push?
bkay