Does anyone know how to check an oven thermometer for accuracy? I just got a new oven, and the old thermometer I had wasn't registering the same temp. as what the oven was set at. Then I got a new one, and the same thing happened; I've been fooling with regulating the temp. controls on the oven (according to the owner's manual), but to no avail; I'm wondering if the thermometers themselves are faulty. I have adjusted the temps on instant reads, but don't see any little nuts and bolts to adjust with on the oven thermometers.