In addition to the outlet grille pop off the front ring and clear any baked lint or hair from around the heater coil and the fan hub; a lot of airflow loss hides there. Skip the concentrator nozzle and use high fan with medium heat to keep airflow up. Also plug it directly into the wall (no thin extension cords or power strips), since voltage drop can slow the fan and make it run hotter so yeah... if it still trips and the thermal cutoff is likely weakening and replacement is usually the practical fix.
Look and I've got toddlers running around and a job that doesn't quit, so when my neighbors started borrowing tools and parking in my spot, I had to shut it down quick. Next time they asked, I said straight up, 'I'm sorry, but I can't lend things out anymore because stuff gets lost.' For the parking, I put a note on their car saying, 'This spot is mine, please park elsewhere.' It worked without much drama.
