So, I replaced a center room chandelier with LED recessed lights. The install went smoothly with no issues for the lights.

I have two three-way switches in the room on two separate walls that control the lights. One switch (Switch A) is used all the time and I replaced the original switch (when the house was built) with a newer switch about 15 years ago when I purchased the house. The OTHER switch (Switch B), however, I never replaced and it is never actively used to control the lights because it's within the shelves of a built-in bookcase. This switch is accessible, just not convenient for use, and functional.

Now, on to the problem at hand: I replaced the commonly used three way switch, Switch A, with a new three way dimmer switch. When I turned the lights on with the switch, it worked for about 5 minutes and then shut off. I killed the breaker, rechecked the wiring connections on the new dimmer switch and also the lighting fixture and everything is connected and correct. I turned the breaker back on, then went to Switch B and flipped the switch and the lights turned on.

I think one leg of Switch B has failed. I will replace this switch but it will take a little time since I have to kind of disassemble some shelving to remove the switch. What are your thoughts on the safety of Switch B at the moment?