For me the problem with intermittent service from the Dyson DC35 was hair clogging up the machinery of the motorised head and causing it to stop spinning after a few seconds, meaning I had to keep pressing the trigger again as you mention.
If that could be it, try my illustrated guide to fixing it at:
http://cusack.eu/2020/12/28/how-to-fix-the-motorised-head-of-a-dyson-dc35-handheld-hoover-that-spins-and-then-stops-while-watching-football/