Bob, what I regard as the greatest weakness in the Greenfield wheel-drive design is that in order to get forward and reverse drive together with automatic belt adjustment, the spring-loaded idler pulley adjacent to the clutches has to take full belt tension when you are driving forward. Because of this it has to have a ratchet system: when it moves forward to remove belt slack, it clicks into a more advanced position, then holds that new position when the mower is driven forward (the load on the idler is much higher in forward than in reverse). The problem is that sometimes the wear is not quite enough for it to click into the next notch, so the belt is a bit loose when driving forward. If I hear about one that goes backward but not forward, I tend to suspect a "between notches" belt adjuster problem. It isn't likely that the reverse clutch will be more worn than the forward clutch. AFAIK the later Greenfields do not have a clutch linkage adjustment (some of the early ones do).
