help- Little heat to feet!

[MustMakeAmends]

I've got an '86 300E w/only very weak airflow to the front footwells, I assume they are not opening up. As far as I can tell, everything else in its climate controls functions as it's supposed to. Turning the fan up higher will give noticeably more air to the side vents if they're opened, or to the windshield, if side vents are closed. I think the rear seat floor vents are getting (somewhat) more airflow than the front footwells...

I did check the center vents btw, they get strong airflow when A/C is turned to Min. But my feet are Cold driving this car w/the heat on- what's the likely culprit here?

I also wondered if the footwell vents can just be forced open easily in the meantime, for the winter months.

In case this means anything, my fan speed pushbuttons do not always work right when first starting out in cold weather, then they "loosen up" as things warm up and function normally.

I posted this Q in this older 5-pg thread, but I'm not seeing it bumped up : http://www.peachparts.com/shopforum/showthread.php?p=1025460#post1025460