I've suffered the intermittent, generally often misfire issue, too. Now, I am a problem solver and modder, so I went through all the possibilities of areas where suspect contact points are. The positive is the first point, where the conductor is pinched vs hard connected between plastic button and battery contact screw and between bottle and positive pin, respectively. No real fix, other than making sure it is pinched well without stripping threads. Next is the battery cap, or more specifically, the threads. Aluminum oxide. Best fix for this area and the third is deoxit. I use deoxit fader grease. The third is the contact between body and top. It's a precision milled surface and any contaminant (grit or oxidation) can interfere with conductivity. I used a light sandpaper here, and immediately gave a coat of deoxit. The final possibility of failed continuity is the 510. The fixed positive pin is a pain for atties that have protruding positive pins, but worse for atties with short pins.
Overall, through gratuitous cuss words and tinkering, I can count on my CV BF. Sad that I've had to invest so much effort into making it work right, but for the value, once the problem areas are identified and able to be improved, it's a great little squonker.
