Tach stopped working

I have a brand new moon sweep style tach,it was working great now all it does is light up and the needle just sits there on 0 any ideas what it might be. I checked the ground and power wire and also the wire going to the coil they all look ok. What else should i check. I hope the tach didnt die already

 

i have one of those,the only time it stops working is when i kick the ground wire loose.you say it's brand new,i'd go over the wiring one more time,and if it doesn't work then send it back.lotta hambers buy moon stuff,they don't wanna hear from 4000 pissed off mofos

 

buy a new one u cheap ba$tard....lol