Based on the different attachment designs I've seen over the years, I'd bet that the two outer screws go through mounting brackets that are attached to the top of the washer. All Westinghouse stack units units attach to the top of the washer at least in the front corners. Maybe investigate by...
RB-130L from 1967-68. Basic Frigidaire 32" cooktop. There's a good chance you have a burnt-off wire as GM Frigidaire was notorious for crappy crimp on terminals.
Discontinued on all fronts
A Google search failed to find a direct replacement, even a generic. But I did find some cross-reference numbers that may help in your search, including details. The P/N you're looking for is GR 209. Good luck!
Newer....
I purchased this set in November 1990. Had it until 2004 when we bought a FL set. We gave this Frigidaire set to our daughter who used it for 5 more years before donating it to someone.