The heater is part number one.
To test the heater you would unplug the dryer.
Then unplug the two wires going to the element.
Take the probes from your ohm meter and put them on the heating element terminals were you just unplugged the two wires.
If you get no reading at all on your meter the element is bad.
If your heating element checks bad you can confirm this by removing the heating element and visually inspecting the coils of the heating element for a broken spot.
If you don't under stand how to use the meter you may want to study this guide.How to use Test Equipment