Hayter Harrier 41 Self Propelled Lawn Mower Lawnmower. I have put a new spark plug on this, cleaned the carb and replaced rubber seals, foam rings. Some black smoke on start up and roller has some debris in it that you can hear when pushing on concrete etc, wouldn't have thought it was the bearings but not sure. If I was keeping the mower I would be to fussed about this but just a point to mention. The self propel pulls very strongly so no worries there.