To add to the link: You can test the thermal link by pulling off the connector and testing for continuity across the terminals labeled 1 and 5.
As shown, but not detailed, you have to pull the vacuum diaphragm off of its mount to get to the hex head bolt holding the resister pack. On mine a 9 mm long socket got the two nuts removed, and then a little prying and pulling on the actuator rod got the diaphragm out.
My old one was crimped into aluminum connectors. I had to file and tin the old leads on the original thermal fuse to attach the new one to them. I used a heat sink on the leads of the new fuse so that I didn't pop it while attaching it.
Fred