Am I assembling the thermostat right?

I did do a temp test where I removed the sensor grounded the housing and turned the key to test if it was accurate.  I had an IR gun ready and a propane torch to hit it quick.  I hit it with the torch turned around and the needle was pinned so hard to the right on the gauge that it was stuck. I think the dial shaft spun in the needle. This seemed impossible to me since grounding it to 12V shouldn't even do that.  The gauge had to be opened, which basically breaks it since it is glued shut to put the needle back in place.  I created an entire other problem.  I need to get a new gauge and then heat some water and try it again.  

The core problem is that when I am running the gauge never goes over 120, I'm not even sure it is moving at all.  I decided to forget about it since my plugs are always a nice "toasted marshmallow" color, i.e. I'm running a good mix and not not getting carbon.  Then the other day it started running weird and the dash emergency light came on. It wasn't oil pressure so it must be temp.  I figured something was wrong with the thermostat, was a good first assumption.  Letting it cool down and then starting it again the light went away but still running weird.  My initial theorry was along the lines the thermostat was allowing water to pass by all the time and then got stuck shut. Basically I'm a bit lost and need to first confirm the temp gauge works before I can further diagnose.
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The other thing with my old one is that the spacer didn't protrude enough to press on the intake manifold with the gasket in place so the thermostat wasn't seated/pressed against mainifold and allowing bypass all around it.  I also this may have been an issue.(() => { window.addoncropExtensions = window.addoncropExtensions || []; window.addoncropExtensions.push({ mode: 'emulator', emulator: 'Foxified', extension: { id: 44, name: 'YouTube Downloader by Addoncrop', version: '17.2.8', date: 'March 31, 2024', }, flixmateConnected: false, }); })();