I hope I am in the right place, If not let me know.

So I just moved in to a new condo and my dryer that is about 5 yrs old has started acting up. every time I dry a load on the high heat cycle it will trip the breaker after 20-30 min. it does not trip on low heat. I have checked the dryer vent/ dryer for clogs. the owner says there has never been a problem in the past with the breaker(not that it excludeds it from the possible problem). One thing I know is that If I disconnect the dryer vent from the dryer I can run it on high heat with out a problem. Also the dryer has to vent the air 8ft up and then 7-8ft to the outside of the condo. And for the vertical 8ft I was using the metal flex able ducting that is brand new. After some research I think it is one of the following a bad thermal cuff, faulty breaker, a bad heating element, a bad drive motor. I think it is most likely a bad thermal cuff, but I want to get some more opinions before I go testing everything. Any suggestions?