the little knob on the dash does not turn in either direction. it would be nice to see if it helps during this cold weather. can anyone give me any tips on how to get this unstuck. it feels like it will break if i force it. help!

__________________
$500 1982 240d owner "Gunter"
125k miles,4 speed manual
crank windows, MB Tex, all original
no a/c, daily driver
Scorecard so far....
$230 Maaco paint job
$27 dimmer switch, $40 shutoff valve, $45 brake MC, $260 calipers, $40 brake hoses, $40 side fender trim, $20 balancing, $109 lifetime alignment, $10 fuel return lines, $115 oil&fuel filters for next 30k miles