The heater blower on my 1981/2 280e is non-operational. I believe the problem is with the rotary switch that controls the blower. It should have at least three positions, but I can only get it to move into two. I want to remove the switch to test it, however I can't figure out how to get it out. I was able to remove the knob but there are still several layers of plastic that prevent me from unscrewing the switch. I also tried to go through the radio opening, but still couldn't get the switch out. Any suggestions would be greatly appreciated. I live in Minnesota and will need good heat in the winter. Thanks.