Go to the Otis section in the Adams Catalog. (Available to download online).Page 253 Item #16 (Brush switch )shows the most common FH switch used in the hook circuit. Sometimes they just get dirty. You can try gently snapping the switch on each floor and checking for wipe. Adjust for wipe if necessary .They have a tendency to crack over time causing it to lose it's tension over time and eventually breaking off thus opening the hall call directional circuit. When they crack,it's right at the base of the switch. I think I've seen one of the other brush switches used before but #16 is used a majority of the time . You'll need a soldering iron to change it.
