You're lucky--I just spent $10 for the same model at a yard sale. IF you find the manual, please let me know.
Until then, I'll experiment using the manual I have for an Oster bread machine. I'll first try reducing the recipe to half, within each bread pan, then see what happens based on how big the loaf becomes. You might have to find anyone's manual and do the same.
I entered www.welbilt.com in my browser and got http://www.enodisusa.com. They're a kitchen-type place but don't feature the Welbilt. My guess is they bought Welbilt, then discontinued all support.