How do I test GE oven High Limit Switch?

Oven is GE JTS3000SN2SS. It hits temperature but won't hold it; temp drifts down by as much as 100+ degrees. No error codes. Replaced control board, and control panel, no joy.

Seems what's left is heating element, temp sensor, and high limit switch. I'm kind of suspicious of that high limit switch, but it's too expensive to try on a whim.

Can I pull it out and test it?

If it's bad, is that consistent with no error codes?

How does it work, anyways? Is it just a bimetal switch that goes open at some temp and closes again once it has cooled off?