1971 Dash / Gauge Cluster Removal

I've told every rally panel owner I deal with.. "DO NOT TAP ON THE GLASS!"
There are a few melt stakes that hold the lens and metal mat to the bezel. When a gauge doesn't act right the driver will tap on the lens. This has zero positive effect on gauge function. You described the malfunction that occurs.
The good news... There isn't a serious fault that requires the car to be parked and panel to be removed right away.
The bad news... the metal mat likely kinked all 3 needles. They'll need to be straightened, stripped to bare metal, and repainted.
Panel removal procedure is found in factory service manuals. I have back problems that prevent my following that procedure so I've developed my own method to the madness. Hope this helps