I have a 1977 Bally High Flyer (https://bingo.cdyn.com/machines/bally/high_flyer/). It is a six-card machine.

There are 3 search units in this game -- one each for cards 1/2, cards 3/4, and cards 5/6.
-- The search unit for cards 1/2 is on the control unit in the cabinet back.
-- The search units for cards 3/4 and cards 5/6 are on both on a dedicated motor at the top of the back door. The search unit for cards 3/4 is nearest the motor; the search disc for cards 5/6 is farthest from the motor. I am pointing to the search unit for cards 3/4 in this photo: http://tinyurl.com/gmxqvdr

The way it should operate is that after shooting 4 or 5 balls, the player presses the C button on the footrail to search for winners. The 3 search units should then each cycle in series looking for winners on each card in succession, stop when a winner is found allowing the player to either play for double using the D footrail button or collect a regular win using the R button, pay off the win (paying either 0, a regular win, or double the win), and then move on to finding a winner on the next card. After the search unit for card 1/2 completes a cycle, it should lock into its index position, and start the search unit cycling for cards 3/4 as it looks for winners, etc. Similarly, when the search unit for card 3/4 completes a cycle, it should lock into its index position, and start the search unit cycling for cards 5/6 as it looks for winners, etc. In this manner, all cards are search for winners and any winners are paid according to the player's choices of taking a regular win or trying for double or nothing.

My issue is that search disc for cards 3/4 will not lock into its index position. It skips right past as the coil armature attempts to engage the disc. In fact, I noted the coil bracket was bent when I got into disassembling the unit.
-- I have completely disassembled, cleaned, lubed all the search discs and associated clutch washers, etc.
-- I have made several adjustments to the coil position on the cards 3/4 search unit using the screws on the bottom of the coil bracket in an attempt to get the coil armature to better align with its associated notch in the bakelite disc.
-- I replaced the coil bracket for the coil associated with the card 3/4 search unit.
-- I believe that the notch on the bakelite disc on search unit for cards 3/4 has become deformed from all of the torque that is placed on that unit, and from general use.

Here is a photo of the search disc for cards 5/6. The coil armature is in the notch, so it is a little tough to see. But the notch is angular and narrow. http://tinyurl.com/hs36xop

Here is a photo of the search disc for cards 3/4. Note the notch is rounded and wide. http://tinyurl.com/zrw2l4v

Suggestions? At this point, I think I'd like to replace the piece with the bakelite notch.

I purchased a replacement bakelite disc and will try that.

It was also suggested that I could just dremel the existing disc to square up and deepen the notch.

Butch -- If you want to PM me your phone number, I'd love your thoughts.

Thanks all. Will update thread with results when I have them.

This worked. Swapped in an exact replacement from another High Flyer. Thanks to Jim Holder for the part!

I spoke with Mike Glauda on the phone who described a fix. I don't recall all of the steps. While it may be an easy fix for him (30+ years of experience), it would not have been for me. Mike mentioned that he may make a video of how he would fix it; if so, perhaps he'll post it here.

Phil Hooper offered his thoughts at the bottom of this write-up:
http://wiki.cdyn.com/wiki/index.php/Cams_Not_Indexing_(Stopping)