Please double check for the model number. It will probably be on a small metal plaque on an edge of the oven door, along the outer edge of the oven opening, or in the oven interior. It could also be on the top of the oven and covered by cabinetry.
Undo the screws that hold the oven in and slide it out 6 inches. You may then find the metal plaque on the top of the oven. You may need the help of another person when you try to pull the oven out, so that the oven does not tilt forward and fall to the floor.
You MAY be able to identify your model of Diplomat oven from one of the images of Diplomat oven control panels here:
Page 6 (PDF document image 7). Note: Use the + icon to enlarge the image.
You may find the image of Diplomat oven knob markings here helpful:
Scroll down that page to the post dated 14-12-14 from pslewis333 to see the image.
Once you know which model of Diplomat oven you have, you may be able to find and purchase decals with the proper knob markings for your oven so that you can affix the decals around your oven knobs. Or, you could use heat resistant paint and a small, pointed paint brush to paint the markings on your oven. With either option, I suggest you seal the markings with a heat resistant clear sealant so that cleaning / scrubbing will not erase the markings.