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Replacement parts for WHIRLPOOL LER6634DW1 ELECTRIC DRYER | AppliancePartsPros.com

See the attachment for the wiring diagram.

As you can see there are a number of parts in the heater circuit.
You could check the heater as visually you can tell if it is blown.
If in auto modes the timer advances then the heating coil and the 240 volts are OK.
If the thermal cut-off is blown there are other parts that should be checked before replacing.

As far as a "common part", I would say a meter is where to start. It will let you check most parts in the heater circuit with the unit unplugged which is the safest way to do it.

If you do not own a meter, I would suggest you purchase a one. You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.

There is a good STICKY at the start of this forum about it's use.