yeah, definitely a common thing.
if it stops when you open the door slightly, then it's not the motor fins.
some folks have found it happens when they have too many pellets in the pot at start up, but mine will do it now and then and i have the pellet feed as low as i can manage and still have it cycle up and sustain the burn
though pulling that motor and cleaning those fins is something i do every year or two.
i'm experimenting this time with doing it every other year.
i coated the fins with spray graphite last two years and when i pulled the motor the build up was minute, so i'm going to see how it goes skipping a year.
with a used stove though, you don't know how long it's been.
but if the sound is the "normal" one then you might be ok till the off season.
and since the sound stops, just like it does when it happens on my PS50, it's a good guess it's that same sound that a lot of the quad pot stoves get.
that's your call though. i just know i don't like tearing things apart when i have to have it running again within hours.
just have a gasket ready when you do pull the motor. (it's definitely when and not if.)
it really is a simple process. i documented it with photos in another thread.
i'll locate that and link it here later.
ok, here's that thread. you'll see it starts with pics of what you absolutely do not want to take apart. lol glad i asked first.
https://www.hearth.com/talk/threads/question-on-pulling-combuston-motor.86932/
after the pics and on page two are more tips for reassembly.
whatever method you use for scraping the fins clean, be very careful not to bend them at all.
a bent fin will unbalance the motor and make things worse than just about any amount of build up you are trying to remove.
i used spray graphite on the fins, but i hear dry molly spray works even better. but either one works pretty well.