Four more broken ones to fix.
Drilled a second location for a screw and nut on the plastic feet.
Bought some stainless hardware at the local hardware store (#6 x 3/4"). The first washer on the right is from aircraft and is made of aluminum. It's rather thick and has a taper on one side.
With the tapered screw head, it's a good combination.
Added felt pads on the bottom of the plastic feet also.