I just got this e-type a couple weeks ago, and I am still working on trying to figure out the dash controls. I am not getting any heat out of the defrost outlets at the base of the windshield. I have tried pulling the right hand lever out all the way and in all the way and I cannot get heat either way. The valve inside the engine compartment seems to move in and out very easily, so that doesn't seem to be the problem.

Is this just the way it is, or am I missing something obvious?
Would it make any difference to replace the heater core with a new one from XKs unlimited?

'69 2+2 4 speed with factory air.