DOM is 2020 and it has been fine until this season. Engine power seems ok. I just stop moving in those gears after 30-40 minutes. These are the gears I use the most while cutting. I can put it in any other gear and keep going (1,2,5,6). My front yard has a ditch and a slight incline. Backyard is flat. Drive belts?
Could be belts but also could be that you have worn a groove into the variable speed pulley and it will give the same effect as a belt bottoming out in the pulley groove.
