i posted this:
every few months, replace the silicone rubber pad under the micro wheel on door. are you soaking it, don't, more than a couple min.
every few weeks remove wheel rubber pad, clean both sides and under the door area. clean/soak the micro wheel and the inside of the wheel too. it help with air too
i bet you're not cleaning the air path well enough. the passage plus the little oval screen and it's path to glass tube and under that little screen itself gets a big amount of oil and crud inside . get a dental prox brush and baby Japanese q-tips with iso and work on it till clean. remove tube and battery before doing it.
clean/soak the micro wheel and the inside of the wheel too. it help with air too
do the mouthpiece path side too. afterwards, do a burn off