How tough to get this off ?

[Already Gone]

So want to change the bulbs in my HVAC control to LEDs and can't get my fat fingers, and neither can a buddy, to get at the tiny bulb holder out to pull it out. So thought I could remove the 2 holding screws and push it back so it hangs to get better access to the holders. Tryng to push it back the knob on the bottom slide wont go far enough back, hits AC hose, so figure the knob has to come of the slide or does it ? I gave it a tug but it didnt wanna budge and don't want to break it so do I just need more force to pull it off and wil it goack on tight if I have to use more force to get it off. ?