How to tell if Oven Control Panel needs to be replaced?

This oven has been very reliable and dependable, only replacing the bottom heating element twice in 14 years. Yesterday the oven was slow to heat, but suddenly heated up and was fine. Today, the top element fully heats when turned on Broil, however, the bottom element does not heat at all and the top element heats faintly when on Bake. We replaced the lower element and that was not the problem. I tested the temperature sensor and it registered in 1066 ohms at room temperature, so it doesn’t appear to be the problem. My next guess is the oven control board, but I don’t know how to tell for sure without laying out a lot of cash and then find out that doesn’t fix the problem. Any recommmendations or similar experiences by other owners?