this is for a Suffolk mower
not enough revs on the engine
speed the engine up till the cutting blades start to rotate via clutch centrifugal force, now engage the clutch by pulling the lever close to the handle, the mover should now drive forward release the lever to stop the drive motion,no drive movement belt is incorrectly adjusted , with the cutting blades spinning you can cut in tight corners just by pushing mower back and forth
wirecutterman, June 2010