Our coach has fold-down arms on the two cockpit chairs. When we bought it, one of the arms of the passenger chair was too low. We figured that someone had put too much weight on it and broken it:

However, I recently learned a trick: inside the small hole at the end of the armrest is an adjustment lever. One can put a finger in there and lift up the lever below the hole, and adjust the resting height of the armrest:

So now yay, it’s all better:

Mind blown! 🤯

Learn something new every day.