Problem With New Vintage Usa Performance Series Tach

So I'm having a problem with the Tach that came with the New Vintage USA Performance series mustang DIY kit package. When I turn the ignition to power, the tach needle should jump, but all mine does is ever so slowly creep up to about 200 rpm reading and then stop. When I start the car, the needle will ever so slowly make its way to about 800rpm then stop. When I rev the engine, the needle creeps ups to about 1200-1300 rpm and stops, won't go any higher than that, and when I let off the gas, the needle stays at 1200rpm. When I turn the ignition off, needle stays at 1200rpm. When I disconnect the battery, needle still stuck at 1200rpm. So when I contacted NVUSA, they said to install a 10K ohm pull up resistor between the power and signal wires, did that, same result. Yes, tripled checked to make sure the switch on the rear of the tach is set for 8-cylinder. All the rest of the gauges in the set work just fine, all lights in the cluster work. Not sure what's going on but I never had an issue with my mini-tach or Sun-Pro tach that I have used in the past.http://newvintageusallc.mybigcommerce.com/67-8-mustang-kit-diy-performance-series-black/

I think I narrowed it down to a bad tach. I pulled out my old SunPro steering column tach that I use to use, wired it up with some pin connectors to plug into the main harness for power and tach signal, started the car and the tach worked perfectly. All the other gauges in the NVU setup were working like they should, oil pressure, fuel, water temp and Speed-O. Ground connection is good as all the back lights worked as they should have when head lights on. Turn signal light flashers good, pony lit up red when I actuated brights.

Tach was bad, sent it back and they fixed it and sent back. In car and now working.