The small oven is a roasting oven, it will run 50 degrees cooler. The small oven is always going to be 50 deg low as that is the calibration of the thermostat for roasting. If you are not going to run the oven as a roasting oven as it is designed. You will want to set the 50 degrees hotter to offset this. For example, if you want an internal air temp of 350 you would need to set the dial to 400 to make it perform.
The Large ovens are calibrated for convection bake and will run 50 deg too low if you don’t turn on the fan as it is designed to be used. If not running the fan you must set dial over by 25 to 30 degrees to get the proper use out of the oven. Our ovens use mechanical thermostats, and they work on averages not exact temperatures.
Also, the blue indicator light is a thermostat cycle light and not a pre-heat cycle light. Please do not use this light to determine if the oven is preheated or ready to place food in the oven. It can typically go on and off about 3 to 4 times during the pre-heat cycle when the thermostat detects an open and close of the thermostat.