I should have explained better . This only happens when engine revs get down to around 200 revs , at the last second it will disengage the
PTO to prevent a stall . We still rely on a slip clutch or belts to take out the shock loads . If it has the same electro system it may be something to look at , check that the park brake is on or maybe check that the
PTO pulse sensor wire at the rear of the tractor has not been knocked off .