New home owner and like doing stuff myself. Heater/ac is on the roof, it will work fine for 3 or 4 days and then it will stop blowing hot. Only way to get it to blow hot again is to shut it off at the breaker and turn it on again. Iv made sure the filter is clean, replaced it, and even tried running it without one. Iv inspected the internals and nothing seems out of place or making odd noises. The only thing that seems weird is it looks like the limit switch has been removed. Either that or I just cant find it. There's a pic of the spot where it looks like a limit switch should be and isn't. Any ideas would great.

Heat went out with both zones calling, checked the burner and it showed TT open. Switched main power off waited 30 seconds and back on, it fired and ran until up to temp, but will not call until power is cycled again. When it is in the state where the thermostats are calling but the burner is not running, it will run if I jump TT without cycling power. This leads me to believe that it is something in the MM-2 controller or the wiring, I've seen the solid conductor wires break over time. The MM-2 is mostly relays and I'm tempted to remove it clean the contacts and reflow the solder connections. Edit: I see that there are two 24VAC transformers so I should check for voltage. The dampers are both open with zones calling. Any other suggestions for debugging this?