Heat issue

I know this issue has been discussed a lot over the years, I've found several helpful posts that have gotten me to a point where I'm hoping someone can steer me in the right direction for next steps...

The heat in my 2003 Tacoma is not working. Here are a few things I've done/observed so far:

I noticed the cable to the heater valve on the firewall was not moving when moving the HVAC controls in the truck. I attempted to move the cable manually and squirted some silicone WD40 into the sheathing, but still no dice. When I removed the cabled from the heater valve, the valve moves no problem. I pushed the valve all the way to the driver's side, thinking I could at least manually get the heat working that way, but still blowing cold air.

I also removed, cleaned and tested the Servo. All seems good with the Servo itself. When I remove it from the notch it works, as in the arm moves when I change the heat dial, but when I reinstall it back into the notch it doesn't move, again pointing to a seized cable.

Is there anything I'm missing? It seems pretty obvious the cable is seized, but if I take the cable off the heat valve and manually move, shouldn't the heat work?

Sidenote: the radiator was swapped out last Spring and this is the first time the heat has been used since, however the hoses on either side of the heat valve are both hot.

 

Inside the airbox there is a door that seperates the hot side from the cold side... try taking the servo off and manually rotating that assembley and see if there is heat then.