Guess I was lucky, but when I got a code 33 on my 7.5 diesel in my '04 HR imperial, I went after it. My gen set is on a slide and when I unscrewed the t-switch , only the top half came out. The lower part was stuck in the bore. I looked at everything and concluded that it would be a major job to take out the housing holding the t-switch , so I first drilled out the center of the part of the t-stat that came out and tapped the hole it fit a quarter inch bolt. Then, I stuffed a rag into the cooling passage below where the remains still stuck would fall into the coolant passage. I then screwed the tapped piece back into the housing and used that bolt to force the t-switch remains to drop onto the rag where I could pull it out. After re-assembly, all has been fine for several years.
Dick L '04 HR Imperial