Gauge cluster grounding issues

[rdc72]

I hope someone can help me out on here? i have a 72 with factory tach and it stopped working. A little back story, i changed out the circuit board and replaced all the bulbs with LEDs, now the tach doesn't work and the lights that didnt work now work and the ones that didn't do? i have tried to put a ground from the back of cluster to the chassis, no go there too? i have tried everything to get this thing to work. any help would be much appreciated.