Oven Retrofitt Project

[Wilsoncs3980]

I bought an old used industrial oven for cheap and but I think I'm going to need to do some upgrades. The oven is an old Precision Scientific. I believe its like 38" x 27" x 26". The power cable is looking pretty rough so I took the panel off to see how hard it would be to replace it and I noticed there are a few wires that have been taken off the heaters. There are 4 banks of heater elements. 2 of the heater banks have 2 power posts and the other 2 only have 1 power post each. There appear to be 3 power switches. One looks like it is labeled auxillary power. I'll try to make a wiring diagram on how it is wired. The control knob for the thermostat is missing. What I think I'd like to do is just retro-fit all the controls. Is there a way to test the heaters to see if they are operational with out powering everything up? I would like to upgrade this to a PID controller and add a fan for circulation. Would anyone be able to help me design the controls for this oven? I'll attach some pictures. The wires look rough but the heaters look like they are in good shape. All the power switches need replaced for sure.

[Wilsoncs3980]

More pictures.

[Wilsoncs3980]

Couple more pics.