Funny you should mention that vent control lever, as I tried to get mine to work better too while I was in there. I couldn't get a good 'shot' at the cable to put some tube-dispensed cable lube on it, at the vent end. I tried shooting some spray-lube too, using the little piece of piping that comes with it , got it everywhere but on the cable itself (no room to aim the bulky can, and it doesn't spray well on it's side). Best way was a dab on the finger and feeling your way in, but....the best result was just spraying into the lever slot! The mechanism for the lever didn't seem 'frozen' anyway, but the lever seemed to be rubbing against the mounting plate. I'd try lubing the slot first, to save the incredible hassle of going in there....

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1986 560SL
2002 Toyota Camry
1993 Lexus