Air Intake Fan

Herb,
First of all, Merry Christmas to you and yours.............
I'm having a issue with the air intake fan on my 640. It struggles to run at normal speed and will almost bring itself to a halt. With just a slight tap on the intake opening it will return to normal speed for a few minutes then bog down again. In fact I'm warming up the offset smoker because I have a feeling it's going to lock up any minute and I cant lose the shoulder I've got on it. Thought's?
Thanks, David
First of all, Merry Christmas to you and yours.............
I'm having a issue with the air intake fan on my 640. It struggles to run at normal speed and will almost bring itself to a halt. With just a slight tap on the intake opening it will return to normal speed for a few minutes then bog down again. In fact I'm warming up the offset smoker because I have a feeling it's going to lock up any minute and I cant lose the shoulder I've got on it. Thought's?
Thanks, David