Whirlpool electric dryer heats but not really hot

My electric dryer turns on but take forever to dry clothes. The heating element in the dryer tub gets warm but not hot. I cleaned the dryer vent out. Anyone have any suggestions

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Section replacement parts for WHIRLPOOL LEB6400KQ1 | AppliancePartsPros.com

I would start by checking the heating element.
Could be it is grounded.

Check the heating coil.
Unplug the unit and both wires to the coil.
Check it with a meter, should be around 10 to 12 ohms.
Then check from each side of the coil to the case/frame, both should be infinite ohms (open). If not the coil may have sagged or broken and is touching the case. This can cause it to run on low.