You do not have to mod your oven to be able to reflow your board.
If you can turn on your oven from the knobs and set it to “always on” at maximum power, you can simply use the supplied power cord to connect the oven to the SSR and, in turn, to the controller. This is the simpler, safer and quicker method.
If you do not have a good reason to start unscrewing the oven you should leave it “as is”.
At least, before opening the oven and start modding it, you should try to make a couple of test to see if the oven needs some modding and to understand which kind of modding would be beneficial for you.
By modding your oven you could:
– add more heaters to improve ramp up speed and reduce cold spots.
– add insulation to improve ramp up speed and to easily maintain a steady temperature.
– drill an hole to the side or the back for the thermocouple
– connect the heaters directly to the SSR bypassing any mounted thermostat and timer
– reduce internal volume to reduce thermal inertia
– consider adding a convection fan if not already present
– adjust the tray height and possibly modify the tray itself with spacers or a steal grill to avoid cold spots on the PCB