Dryer with low no heat. troubleshoot parts?

Please help. I have looked all over the forum for several days. Where do I find how to test specific components for this dryer. I have not opened this unit up, but I can. I attached a photo to aid in the identify of which model (good/best). I’m unsure of what parts to test and if they are obvious? Am I just looking just to measure resistance and not voltage? The dryer has some heat (very minimal) on some settings, other settings have no heat. I really need to get this up and running. Thanks for any suggestions…