If you want the mower down to all metal 100% then the aforementioned strategies will work. However, I rarely bother with getting ALL the paint off of anything. I usually use a combination of oscillating sander and hand sanding. Just to get the surface smooth and clean. Then just prime it and paint it.
If you need it down to bare metal and don't want to work, then try Strip-Eze paint stripper. And then Naval Jelly to reverse the rust.