I have 2018 21C with 3 burner top and oven. I cook a lot, and have tightened and replaced the burners many times. the screws will eventually strip out the burner holes and you will need to replace the burners. also, after some time the burner will warp and need to be replaced. I don't bother with locktite, I think the burners get hot enough to neutralize locktite,
IMO the design is weak, not meant for a lot of use. I keep new spare burners in my trailer and can tighten or replace one in very little time. 1st thing get out the manual and read how the take off the top so you have access to the burners. 1st time I took mine off, I didn't know how and damaged the top. no worries, I did a work around and have 2 screws holding it on, haha. cheers