Joe,
You aren't having much luck. LOL
What would likely remove it is called an impact screwdriver. I attached a pic of one below.
It is designed to loosen screws like you are dealing with. How it works is this. You secure the head needed into the screw as best as you can and then you smack the back of the tool with a hammer. When that happens, you have all the inward impact of the hammer hitting it, and the tool is designed to turn a little at the same time to break the screw loose. I've had to use one a thousand times. And yes, they work well.
If you don't have one, check the parts store and see if they have one, they will lend you. Other than that, they are not too expensive online. I've seen them for under ten dollars.
Let me know if this helps.
Take care,
Joe
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Sunday, April 24th, 2022 AT 6:44 PM