I’ve been thru this exercise
The steel arms have a welded pin in them
There’s a specific arm built for each right and left
In the manufacturing process, there are inconsistencies
Here are your options after you remove arm from seat back:
1) once you understand the mechanics of the arm, place a “shim” between the pin and the point where the pin rests when on the down position. I did this by using a metal piece fastened with JB Weld inside the seat back. It’s held perfectly for over 2yrs
2) take steel rod out of the padding. Grind off the pin, then drill hole in arm &
weld a new pin in the proper location on the arm
The area where the pin rests inside the seat back is very difficult to access
Once you understand the mechanism, you can then proceed with your desired fix
By the way...use the SEARCH function as this topic has been previously discussed