I have an older Viking Dual Electric Double Convection Oven. The serial number has been scrubbed off, so I can't read it and order a manual. It has 4 knobs across the top, 4 smaller knobs in a square formation in the center and the words "Viking Professional" are on the top oven door on the lower left of the door. Is there any way you could tell me the model number based on that description? Oh, and it's a 30 inch oven in stainless steel - electric. Thank you.