I'm glad I could help. If you have problems you may need to thin your paint more. Try it with food colors or ink to see what it can do.
The nozzle doesn't have to be very tight to seal. You will see bubbles in the cup if it doesn't. You can probably get away with leaving it in place and flushing out the cup with an eyedropper and your cleaner of choice. I use a pumping action. Then pull the needle and wipe it clean. A dab of needle lube wouldn't hurt.
Don