The 987.1 and 997.1 are notorious for “soft touch” coatings on the fan, temp, and volume/tune knobs that degrade over time. You end up with sticky buttons and black tar like substance that comes off on your hands.
Fortunately, there’s a company called Climarepair that sells replacements. The knobs pop off and right back on; it’s a 2 min job. The fan and temp switches require some disassembly of the center stack, and then taking apart the control panel, but it’s really no more difficult than swapping a hard drive on a laptop.
The improvement is dramatic. Pics only tell part of the story, because you no longer have to deal with the unpleasant stickiness.
Before:
After:
