Cams Not Indexing (Stopping)

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Case Study Summary
Game High Flyer
Games Applicable To all
Source robert medl
Problem Reported search wipers not locking in index/home position
Fix confirmed


Robert writes:

I have a 1977 Bally High Flyer which 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:

3-4 search disc/wipers on High Flyer

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:

5-6 search wiper locking cam on High Flyer

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

worn 3-4 search wiper locking cam on High Flyer


The cam locking notches in the bakelite disks can wear. While some wear is normal and inevitable, wearing enough for the indexing/locking to not work is fortunately rare.

Before assuming that a slightly rounded notch lip is your problem, make sure the indexing plate can drop all the way into the notch, and the clutches are lubricated. If you put some extra pressure on the relay plate/armature with your finger and it still won't hold - or the cam releases as soon as you let go - then a worn notch is likely your problem. 


This machine has three search disks. Two are fine, one is bad...why? The most common cause is dried clutches. If the clutch doesn't slip easily, then the index plate slams into the locking notch wall on the way in, and scrapes away the notch wall on the way out.

You've got the usual three options:

  • repair
  • hack
  • replace

In this case, there's not much difference between repair and hack. You can't add back bakelite that is gone, and I doubt something like epoxy would hold up to the forces without chipping off eventually (but it might). Somehow you need to make a sloped notch wall vertical again, and the simple solution is to file/cut the slope out so you have a restored the vertical notch wall.

On many machines, the locked position of the search wipers is flexible. There's an arc of rivets under the wiper contacts that aren't connected to anything, so if the locked position varies +/- a rivet from the standard factory setting, no harm done. In fact, the normal factory position has the wiper contacts between/bridging rivets...all that matters on some games is a switch stack is lifted by a pin when the wipers are locked.  If you cut out the slope, the locked position of the wiper fingers will shift a little, but you can adjust the switch stack if needed to be back on the pin and you're good.

On many of the six-card games, though, the wipers must be locked on a specific rivet - it's the only one that isn't connected to game circuits.  Get it wrong, and the payouts will misbehave. If you cut out the notch, the wiper contacts will likely shift and lock on a rivet that is connected to game circuits. You get payouts on cards when a win is detected on a different card.


The simplest solution on a game where the wiper lock position is critical is usually to cut the notch and adjust the index unit and switch stack position so the wiper contacts are in the correct place when locked.  Depending on how much you have to cut, you may be in the adjustment range of the parts and you are done.

If you cut out more than the adjustment range of the index unit/switch stack can handle, you'd need to elongate the slots in the mounting brackets so you could move the part more, or worst case drill and tap new holes for the mounting screws.

If you are willing to take the shaft/wiper assembly apart and have a parts machine, replace is an option - either just the locking cam (That's what Robert did) or the entire wiper assembly if it's the same.

I suppose it may be possible to remove the cam from the wipers and flip it/reposition it, remount the switch lifting pin (in any), cut a new notch in the right place, and slope the old notch even more so it does nothing. Seems like a lot of work compared to just cutting the existing notch and moving the associated parts as needed.