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Replacement parts for Whirlpool IED4400SQ0 29"ELECTRIC DRYER | AppliancePartsPros.com
See the attachment for the tech sheet.
There is 240V across the main power wires
I am assuming that tis was checked at the terminal strip in the unit.
Both the high and low limit thermostats have 120V at each wire and 0 ohms across the terminals for each thermostat.
I am not sure what you are calling the low limit?
The heating element doesn't appear to be physically damaged.
It is best to actually measure the heating coil.
Unplug the unit and set it to mid-cycle heated timed dry then attach one meter lead to L1 and leave it there. Then work your way back through the heater circuit. Everything should be 0 ohms till you get to the heating coil then one side of the coil will be 0 ohms and the other 8 to 12 ohms.
If all OK then you know that either you have a bad wire or a problem with the motor's centrifugal switch.