Yet another blend door question..

[Pat B.]

I've searched the threads and haven't found anyone with this problem. Overnight, my '01 XLT (manual A/C) decided that, after it warmed up, it would only blow cold air thru the vents. I get heat for a minute or two and then nothing but cold. Thanks to the smart folks on this forum, I isolated the problem to the blend door / actuator. I pulled the actuator (that back bolt is a real PITA) and discovered that the blend door appears o.k. - moves smoothly, doesn't bind. But the actuator appears to work o.k. too, as long as it isn't installed. While R&Ring the actuator I noticed that the D-shaft wasn't lining up with the top of the blend door. They're off about 30 deg. and in full heat the actuator is trying to close the blend door beyond the point it's willing to travel. I simulated this myself by holding the D-shaft while rotating the heat knob. Sure 'nuf, the actuator would try to turn, give up, and retract to the full cold position. So my question: is there a way I can figure out if the problem is with the actuator (slipped gear?) or the blend door (something blocking it from closing all the way?) without pulling the dash to get to the plenum or spending the $$$ for a new actuator? I'm hoping someone here may have run into something similar and can steer me in the right direction. Thanks!