Stuck heater cable on '90 240sx

[dragonboy240sx]

Got a puzzler here. My Temp control slider on the dash is stuck. The slider won't move more than 1 inch from the cold side! I've removed the dash and found where the cable leads to... behind the heater! Going to be removing the heater today to try and figure out why the cable is stuck. I wouldn't care about it but I need to bleed my coolant lines... and this is keeping me from doing that...

So has anyone else experienced this before? I Just did a SR swap on this car. But the heater wasn't touched other than disconnecting and reconnecting the coolant lines. The car has been sitting for quite some time. But it never had this problem before the swap. Any help would be appreciated!