If you have to turn the knob loads of times, then chances are it's the contacts on the board are dirty and the wiper on the back on the rotary knob (the clear bit inside - not the cover that you pull off - so have to dismantle the unit.
It's one of the things I do on all the HEVAC units that I service, and pretty much all of them are tarnished, and the tracks on the board are dirty.
To clean the board, I use contact cleaner/isopropyl alcohol, and a cotton bud. To clean the metal wiper, I use high grit sandpaper, or emery cloth.
On my website, on my 'Technical Information' page there's instructions for installing my pixel fix shows the unit being stripped apart and the track on the board/and the wiper that gets dirty.