Removing the Playfield is probably gonna be more than one Jones plug I have four on my gottlieb‘s. That being said if you’re really concerned about the spring that’s a good way to start. If It was a gottlieb and I couldn’t find it and had another spring I would assume it’s underneath the lower mechanical board and start the game and roll the dice.

Been there. Many times. Like Judoratt says it usually ends up under that bottom board where you can't see it. Sometimes you can get lucky by dragging a magnet under that board. If you've inspected all the relay switches and don't see anything, you are probably alright. Fuses are your friend.

Been there more than a dozen times with a nut or washer that gets away. Unplug the machine for the wall, if not already done. Tilt the machine to one side ( to the right, or left ) and block the front and rear legs of the high side with blocks of wood. You only need to raise it like 4 or 5 inches. With the palm of your hand, pound on the bottom panel from underneath the machine. Don't pound so hard you break the board. But don't be too gentle, either. The vibrations and the tilt angle will usually allow anything hiding under the relay panel to move to the lower edge of the cabinet. Fish these out and hopefully your spring will be on of the treasures found.

One of these is handy, under the motor board, down the drain...

https://www.amazon.com/gp/product/B01A0HKTG2/ref=ppx_yo_dt_b_search_asin_title

I've done it with Gottlieb's. don't see why you can't with Bally.

Yep.

If it still doesn’t turn up, fire the game up and live on the edge. The worst case is a game function won’t work right and then you’ll know right where to look.

Those springs can end up stuck on a wiring harness and really tough to find sometimes.

The mech board in Bally games is secured by 2 large screws. Remove the playfied and unplug all of the jones plugs to and from the mech board...feed the power cord back and remove the 2 screws...then lift out the mech board. It should take 15 minutes the first time..much less after that. Its much easier to inspect when out of the cabinet.

I've had success finding the unseen using a vacuum with a piece of cheese cloth or 'donated' nylon stocking/panty hose over the hose. Crevice tool for open areas and deep recesses, soft brush attachment when hovering around mechanicals. <Unplug machine of course>

Also when inspecting a bright direct beam at a side angle can pick up out of place items better than overhead.

Cheers

Tom

What Bonzo71 said! In the time you waste trying all of the other methods, you can have that entire cabinet emptied. I agree it will probably take you 15 minutes your first time, but once you know what your doing, you can have everything out in 5 minutes. I suggest you put a white sheet on the floor as you remove the playfield and bottom board. Give them both a good shake over the sheet.

I've learned my lesson as well. So now I use the towel method when working on the bottom of the playfield.

Towel (resized).jpg