I have good heat into the cabin; when the dash control is set to floor. But, when the control is set to defrost, I get little or no flow on drivers side. A fair amount gets to the passenger side.
I’m lookin for advice on how to reset the cable/valve connection first.
My second thought is something fell into the defrost vent - like a parking stub ? Can the valve be removed and opened up without removing the fuel tank ?
A couple of picture attached for a view ( not my car ) but might help

Can you remove the paper tube in the footwell from the diverter and enter it from below?
Just enough to stick a vacuum hose up into it.

I tried that and set the Vac to blow; footwell vent is fine, defrost vent weak.

Jim, I took mine apart when I added AC and found a pencil in it. I'd previously wondered why the slide control would only move 1/2 way across. That entire piece and the 90 can be removed with the tank in place. IIRC - its been 5 years - I needed to remove the vent louver in order to remove the 90. Can't remember why now. But yes, the vent 90 and the junction box on the left side comes apart with tank in place.
EDIT: Just remembered that there are 2 nuts you need to remove behind the louver in order to remove that assembly. And I believe there are 2 more you access from below.

I see the nuts under the dash. The red slider does move all the way over to the right; it might not be moving the valve enough ?
Dam hard to see what the range of motion is from outside the valve

The closed position - Defrost position

This may help chasing cable connections:

Click to view attachment

Click to view attachment

Thanks ! I double checked, cables are right.

Good thread I'll bookmark for later. My tank is out for painting along with most of this stuff. Oddly, never taken all this out before. It'll be interesting putting it all back together.

I would mock it all up on the bench and see how it works. Then you can “preset” the three cables connections.
And, the nuts on the valves that hold the cables are 7mm.

Couple of other links:
http://www.914world.com/bbs2/index.php?showtopic=86942

https://914electric.wordpress.com/2011/03/18/take-the-heat/

@Root_Werks

Perfect, thanks!