How to disable voltage limiter inside gas gauge?

Hello Friends,

I have attached a picture of the back of a 66 Barracuda gas gauge. The voltage limiter that produces 5V for all the other gauges should live inside the gas gauge. I wish to disable or remove the old voltage limiter and instead use a modern 5V solid state regulator. Another FABO has stated that you can disable the internal voltage limiter by blocking its ground connection with electrical tape, hence the tape you see on my gauge.
However, when I test the gauge, I find the 12V terminal shorted to the 5V terminal, which isn’t good. By the way, the gauge works well. I applied 5V to the 5V terminal, then applied 10 Ohms between the Signal terminal to ground. The gauge needle correctly went to Full.

But can anyone advise how to disable or remove the old internal limiter?

Thanks,
Kevin