Well NormK you should by now hopefully know we the model and type numbers of the engine so we can get on the same page. I learned not to guess at things as these could either an air vane governor or a mechanical version. It is because I don't see many push mower any more as the repair costs are nearly the same as a new mower around here.
If a mechanical governor it may simply be out adjustment and a static adjustment may resolve the problem.
