Got it working and the needle out. Turned out the valve for the can wasn't getting in far enough. Had a washer in the lid top that is too thick, without it works ok with very little leakage. Probably just buy a new can top, or just switch over to the air compressor to play with. Ran some cleaner through after cleaning up the needle, and got some nice green dissolved paint. Got it running clear now, figure I'll run some more cleaner through it again later today if any more old paint dissolves.
Next question is how far does the needle come out of the end of the gun in a ideal world?