BROKEN HEATER CONTROL

[TaggyCar]

The sliding control (middle one) has snapped off and is now in a central position.
This control was very stiff before it snapped off and wouldnt slide without moving the top slider.
How do I get the cover off to see whats happening with the sliding controls?
Thanks Steve

[Simon]

Could be part of the stereo wiring that has jammed, might be worth removing the stereo first and having a look through the gap.

[TaggyCar]

Finally got round to it. Took the stereo out and could see that the heater control cables were badly routed(retro fit aircon pipes and switch in the way). Have re-routed them and it will hopefully do now-Pig of a job as there was so much crammed in there
Thanks for the suggestion Simon!