Seized Heater Cable

The heater cable on my 69 G10 is seized up. And the air and defrost cables are really tight, but do move. This is a two parter:

1. Can I remove the air distribution box under the dash without removing the heater core and/or heater motor assembly? All the flaps inside need lubrication and realignment, and I'm hoping I can do that without removing everything else.

2. Are replacement cables for all three available anywhere that kind of look OEM?

It looks like a one-piece shell to me, so my guess is that you would remove all to clean , lube, and adjust.....
As for the cables..... remove them and start working them with wd40..... soak the entire length while bending and working it to get the lube between the coils of the outer wrap.... If that's too much hassle, consider coiling it in the bottom of a bushel tub and submerging it in diesel fuel or ATF for a few days....It should be free by then.... clean up with wd40 and try to work graphite in at both ends and between the coils of the wrap....The last step is cleaning with WD40....