Contactors are getting weak and need to be replaced.............the buzzing is the magnetic coil making noise. Anytime I hear a contactor buzzing on a furnace, ac, or refrigeration rack I replace them immediately. Otherwise what happens is eventually it will get stuck closed (on position) and cause a issue later. I’m happy to assist further over the phone at https://www.6ya.com/expert/robert_54ae41aaaffbab00
When the light is on, it is the heating element coming on to recover lost temperature. It is just the thermostat and the element working correctly. When the light is on, it is heating, when the light goes off, it has reached the 'set temperature'.
Nice commercial oven, I am a chef retired.
https://www.google.com/search?q=duke+e101-ev+manual
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After confirming correct installation of the blower it might be wise to check the pressure levels of the valve connected to that burner that releases the gas. There should be a way to adjust the flow of gas out of a particular burner. However it is advised that you do not use the fan unless you need to and consult a service repair person or consult an expert here https://www.6ya.com/mr.mike that can guide you thru the process of resolving this yourself.
thank you for your visit
When you have a high end oven like this you will find that the manufacture stands behind it. try to find a 1800 number and talk to parts. they will probably want you to talk to an approve alliance repair person but if you ask the right questions and listen between the lines you might find out what you need to know to fix it.
