Rusted Screws Jenn Aire

I had a bad spark electrode on my right from burner. Jenn
Aire JGS9900BDS. I ordered a new spark elcetrode from you. (Top burner ignitor http://www.appliancepartspros.com/whirlpool-top-burner-igniter-74009336-ap4100764.html)
So far so good. Unfortunately, the screws holding down the burner assembly were rusted in place–"welded in place" by rust. Despite high quality loosening oil applied and long sitting time, I had to cut off heads to remove burner assembly. I still cannot get screws removed by turning on remaining post of screw with vise grips. I will try drilling out and using left handed drill bit but I think will need to buy new holder orf as well. (Part Number: AP5668984) as I do not think I will be able to remove screws remnants. I also will need a new front right burner assembly as the screw that holds the spark electrode to the burner assembly (Part Number: AP4098018) was also unremovable. Ugh.

Unfortunately, the from left burner seems to have the same level of corrosion so what do the 4 screws holding down the left front dual burner go into? If if have to cut off those screw heads to get that from left burner assembly off (so I can pull of the top of the range to fix the right front burner (installing a new burner assembly and new holder orf (Part Number AP5668984) will I be able to install a new receiving part for those 4 screws???
This has turned into a bit of a rabbit hole. Any comments/answers?
Thanks!