So, this just arrived 🎉. I’m feeling excited about getting nerdy with leather thickness

Hi Dave.

On my gauge, you undo a small locking screw and physically turn the entire dial face until it matches up to zero. The fact that your dial has knurling on the outside for grip indicates this will be the case for you too. The needle never moves from its current position.

Note that '0' on the dial will no longer be in the 12 o'clock position after doing this. This is considered normal.

Send more pictures or a short video of the outside if this info isn't helpful.