always be sure to regularly check that the thermocouple is properly seated against the glass. we’ve destroyed a few of these because the thermocouple wasn’t reading the temp properly and the heating bands overheated.
Use Kapton tape to secure thermocouple. POPE thermocouples tend to pull away (at least on their 4" model) and the oil jacketed bodies are better than the heat banded (better meaning aren’t prone to cracking).