Dryer runs fine but doesn't heat
Thermal fuse? Or heating element?

Dryer runs but doesn't heat

More likely thermal fuse or thermostat. Possibly restricted vent hose

Don't forget the relay, a frequent trouble causer. I hate to say this, but did your cleaning include the lint screen?

To do simple checks like this you do need some tools. A test light, a meter, or a voltage detector might be the best place to start with. I came across the niftiest gadget for trouble shooting, a voltage detector. They work through the insulation of wires. There are several brands. I have a GB Instruments GVD-505A, less than $15 at Home Depot. Touch it to a hot wire, and the end glows red. Find the doodad that lights it on one side, and not the other, and you have the culprit. You do not have to open up housings and expose electrical contacts. You are looking at where your hand is, not where the meter is. Most people are capable of doing repairs and will get it going and not get hurt if they use a little sense. The voltage detector makes it even easier.

I have a thud noise when dryer is running