alwood,move your gear box back slightly towards the back axle 5mm.on your middle photo it shows your tension pully has tension on the belt(pivoting towards the left of the frame where as mine is in the strait line position with the pedal virtually straight up and down until you start putting slight foot pressure on it.ry to take pics of mine or i can take measurments if you like.i consider these a very good and robust mower,how wide is your belt-i recall the"a"type are narrow and the "b"type are wider.the latter mainly used for driving blades and final belt drive on some mowers...ken
