The front left element of my Whirlpool range top, a dual 6 and 8 inch unit that has a simmer function stopped working. By that I mean it would not regulate via the knob when it is in normal function. For example, if I turn it on low (for both the 6 and 8 inch elements) it turns on high. The simmer function function seems to work just fine. Thinking the element went bad, I purchased a new one and I still have the same problem. I don't know much about stoves but the limited research I've done suggests it could be the infinate switch. Does this sound right? Second, are they hard to replace? Third can you direct me to a part number?

Thanks in advance!