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Replacement parts for WHIRLPOOL LER8648PW0 | AppliancePartsPros.com

Here is a wiring diagram
https://www.servicematters.com/d...0Sheet%20-%203979703.pdf

The element does not look cracked, but does not heat outside of the cabinet either.
Not sure how you tested it outside the unit so cannot say if it is blown or not.

How can we tell if this is an element issue or a thermostat that needs replaced?
Get a meter and check them.

First though turn your breaker off/on slowly a couple times. Sometimes you can loose half the line without actually tripping the breaker. Symptom is no heat. Better yet check that you have 240 volts at the plug.

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.