Heat unshrink

I was setting up to run a job after just finishing a job, when suddenly I saw the left side y-axis was not in synch with the left side. That’s when I noticed the right side belt has no tension practically at all. Then I noticed the little heat shrinks that hold the belt looped around the tensioner plate was not as shrunk as previously. Obviously nobody uses the heat shrink anymore, but it’s been good since 2015. So I restretched the belt and meshed the teeth then hit it quickly with a heat gun, and it reshrunk the tubing. Tightened the tensioner and back in business. I didn’t know heat shrink could unshrink.