Dishes are not dry at the end of the cycle.
Here are your parts
http://www.appliancepartspros.com/parts-for-whirlpool-wdf530plyb0.html
See the attachment for the tech sheet.
FYI the last 2 digits are B0 not 80.
Check the heating element for signs that it has burned out.
Check that heated dry is on.
Open the door during the dry cycle to see if the heater is working.
Be careful that you do not burn your fingers.
Check that you have rinse aid in the dispenser.
If the heater is off during dry, remove power from the unit
Check the hi-limit thermostat. Should be 0 ohms.
Check the heating element. Should be about 20 ohms.