I was using my droid this weekend and right out of my gear bag it was breaking paint (fist broken ball in the gun since i've owned it). I always clean and make sure my gun is properly lubed and running at proper pressure before each day so it was a mystery to me. I checked the battery with a tester and it was still a really good battery. but i noticed the clip that holds onto the 9v battery (harness side) was spread a little to far, so even though the battery was clipped in it wasnt making full contact. I used a set of pliers and gently crimped in the prongs (be very careful) to get better contact. The gun ripped the rest of the day without a ball break. I just thought I would post this as something to look for if everything else is right on your marker but you're still breaking paint.
MD for life!