Diagnosis
The Kontrol Tower vent is seized due to carbon and grease buildup on the internal threads or stem. This happens after high-heat cooks without cleaning.
How to Fix It
Allow the grill to cool completely. Remove the Kontrol Tower cap by unscrewing it counter-clockwise. Soak the cap and the threaded stem in warm, soapy water. Use a soft brush to scrub all carbon deposits from the threads. Dry thoroughly. Apply a small amount of food-safe, high-heat lubricant (like Kamado Joe Ceramic Grill Grease) to the threads before re-installing.
If That Didn't Work
The internal stainless steel stem may be bent from impact. Inspect it for straightness. If bent, you must replace the entire Kontrol Tower assembly (Part # KJ-161000 for Classic III). Order from Kamado Joe.
Heads Up
Never operate the grill with the Kontrol Tower completely removed. The stem is the primary structural component holding the top vent plate in place. Operating without it can cause damage.