Well this is embarrassing...
When you pull out the CRT on this big machine, it hits the door switch unless you lower the front, slide it out a little ways... then just pull it out normally and that way it clears the button.
The first time, I ran the CRT into the button and dislodged it. I pulled out a wire from the switch (to remove the switch) and replaced it later. DING! That was my problem. I didn't put the wires in the same spot!
They go in the top two tabs... so the switch is open when the door is closed. Otherwise you get the constant door open error. Disconnecting it works also, but I didn't feel like tying the wires up.
I wonder why this has a switch anyway since it's got the optics in it? Just extra security?