It sounds like you need to clean out the smoke unit. Over time, they can get "gunked up", especially switching back and forth between smoke pellets and liquid smoke. At the bottom of the smoke unit bowl, there are little holes that allow the puffer piston to force air up through the unit and out of the smoke stack. If those are clogged, you won't see much puffing action at all. While your at it, you can replace the wick material.
Do not stick anything down into the unit to scrape around. You will likely break the small wire in the heating element.
