Paasche D500 Compresor trouble

It may have died from overheating as they do.

If I recall correctly, the D500 is a diaphragm compressor without a tank. This means that it needs to be able to bleed excess air when you're not actually spraying (ie. when you are not depressing the button on your airbrush.)  If it's all sealed up without a bleeder, then running for a few minutes without spraying may cause it to jam up due to excessive backpressure in the output side of the system. .

Simple test - run the compressor without the airbrush attached, ie. no load. If this works then you may need a bleeder.

EDIT: I have just checked the instructions as per the link above. It looks like a bleeder valve is supplied - make sure (a) it's installed and (b) it's not fully closed.

     Thanks for the Link, I have already checked the diaphragm and head, and those parts seem to be ok. I was hoping that before I went pawing around any deeper, someone who had encountered this problem before might be able to shed some light on what could be wrong.

Did you check the directions?  Page 2 of the instructions discusses how to service the compressor.  Here's a link to the instructions if you've lost yours: http://www.paascheairbrush.com/2005_parts/D500-50%20Air%20Compressor.pdf

Hope this helps.

Jesse