Anyone else have this happen? My CC pushbuttons (in 1987 300D) get stuck in the "down" or "on" position. Usually when I push "0," whichever one was depressed pops up. No longer. No I have to finesse them up, and sometimes they still don't go. What's causing this, and is it fixable? (Or replaceable?)

While we're on the topic, here's a question that I stumbled across today. In the owner's manual, which I thought I'd read all of, I realized today that it says the "0" setting is only to be used "temporarily" while driving? I always thought that was basically the "off" setting and I use it all the time. What setting am I supposed to leave it at if I'm completely comfortable with no heat coming in? The CC works decently at keeping the cabin temp great (not too hot) if it's cold out, but if I leave it on when it's say, 70 out, it would get too hot.

FWIW, the AC compressor is not hooked up, so that's a non-factor whenever I talk about CC.

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1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
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1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)