Diagnosis
This is the convection fan motor or its associated components. A loud hum indicates a failing motor bearing or an obstruction.
How to Fix It
Check for any foreign objects (foil, food debris) touching the convection fan blade at the rear of the oven. Clear any obstructions.
If That Didn't Work
The noise points to the convection fan motor assembly itself wearing out. The motor requires replacement to resolve a persistent bearing hum.
Heads Up
A light fan noise during convection or self-clean cycles is normal. A loud, grinding, or intermittent hum is not.