I've had my Pax since the beginning of August (5 months) and rarely clean it more than just wiping it out. My oven has had black crud caked on the walls for at least two of those months but since a few days ago it has seemingly been overheating, tasting like garbage, and giving dark med/high abv on yellow low setting. I thought about sending it back but thought I should clean it first:
First I cleaned the screen and the tube, there was a mild improvement but it still seemed like med abv/harshness on low.
Soaking the MP in iso made a big difference in taste! (I had just been q-tipping it and not smelling it lol)
And chipping the crud off the oven walls and going over it with Magic Eraser got rid of the harshness that I thought was a temp malfunction!
I think I'll be using that stuff more often, it's just like open cell foam and cuts like butter with a knife so you can make a hundred little chunks out of one eraser bar. I stick a slightly wet mini-slice in the oven and use the back of a pen to scrub it around and it looks shiny like new!
A clean Pax certainly is a happy Pax...