I'm at 3005 on boxing...and I suck at the bag. I don't think your nunchuck is faulty. I have found that the more I box the less responsive the nunchuck becomes (just for that boxing session.) This absolutely kills me when playing the computer b/c when it doesn't respond it leaves me wide open for a combo from the computer. The nunchuck works just fine in my other games. When I am able to get my punches to respond I find that alternating hands makes me land punches faster. I think the secret to the bag is probably a combo of a couple of fast punches followed by a big dominant hand hook or uppercut, but my best on the bag is 25 so I really have no idea. If anyone has any bag pointers let me know.