Resurrecting an old thread because I have a similar question.
I, too, have noticed that some of the early woodrails do not have a bell. Two of my games were missing either a bell, or the striker (A1150) in the previous thread. Looked similar enough to Robo1's. Easy enough to fix since the bracket that holds the coil has a screw hole to attach a bell to the bracket.
So, I'm investigating the "silence" on one of my machines and I disassemble the stepper unit and notice that the bracket that hold the coil does not have a hole for a bell. Curious, then, were some made purposely to NOT have a bell? Also, why are so many missing?
stepper no bell (resized).jpg