If you get a valve that is stubborn to the point it looks/feels like you will damage it by disassembly and doing the job "correctly". There is a way to "cheat" it. I've had to resort to it. (particularly on the Wolf) as those valves had particularly stubborn screws with recessed heads. And they're not budging. So, here is my "magic sauce" for that issue.
Small wire brush like this
https://www.harborfreight.com/brass-detail-brush-69524.html cleaning all around the stem and retainer as best as possible. Spray off residue with a little BrakeKleen (though not directly into the stem but across it). Then I hit it with a drop or two of good ol' ATF. Any kind. Work the valve wipe clean and repeat if necessary. The valve WILL work better and actually work if it was totally stuck prior.
It will NOT work as well as doing it fully as was outlined in the video. But, it WILL save one that is not working.
I did this on my Wolf as I had valves nearly locked up completely when I got it home. Had it all these years (and on that beast those valves get HOT. It's still going fine to this day. Is it as good as it can be? No. Not by a long shot. But, it was this of likely scrap the entire grill.
This should always be a "last resort" type of fix IMO. but it saved mine.
Now why the ATF? Well it can take quite a lot of heat and not harden. It's a penetrant as well as a lubricant. So it can get it's way into the shaft and do it's magic. ATF is really good stuff for oddball things like this.
But, honestly I would still like to get the valves apart.
This worked (works) because on a stuck valve 90% of the issue is at the stem and the stem retainer. But there is still debris inside it and corrosion, along with the grease from the factory that will have hardened and oxidized over time. So it's NOT A FIX it's a "workaround" at best.