New FC member here (2nd post). I found and read this thread when I began having mouthpiece issues with my Pax. Lots of great info here. I decided to join so I could share my experience.
I did not clean my Pax soon enough. It got quite gummed up before I cleaned it the first time.
I gave it a thorough cleaning with iso. I did get some iso in the temp button area, but have had no ill effects because of this.
The mouthpiece action did not return to normal after the first cleaning. This got me worried. I thought I might have to send it back, but I didn't want to be without it for any length of time! I cleaned it a second time, again with iso, but I heated it up first. I also soaked the MP in iso. I'm happy to report that the MP action has returned to normal. Very happy with my Pax (my first vape).
I believe I've identified a factor that contributed to getting the mouthpiece gummed up. During the first couple weeks, I often laid the unit down horizontally between hits. I believe this allowed warm resin to run towards the mouthpiece. Now I always set it down vertically to prevent this.
I will also be cleaning the unit very regularly from now on. This isn't a big deal, as it only takes a few minutes, and the unit cleans up very nicely.