The new Cranks have 3 cap head bolt holes in them to grip the flipper shaft.
We are going to hijack one of the holes to mount a little spring wing arm. The arm is just a piece of "L" bracket. This allows us to avoid the junky Compression Springs, and use the much superior Extension Springs.
Compression Springs ALWAYS break. They also scratch up the Plunger Shaft, putting more wear on the Coil Sleeve and transferring less power to the flippers due to the increased friction.
Wipe off the waxy protective coating on the new Plunger Shafts with Naphtha so you don't contaminate the new Coil Sleeves with sticky goo.
Flip the coil orientation around so that the lugs are away from the Coil Stop. This will keep the vibration from breaking the fine coil wires off at the lugs.
Adjust the EOS Switch gap so when the Plunger is fully pulled into the coil, the switch is opened 1/8" . Not more, not less.
Now when you play your downgraded Bally, you will have solid flipper control and better than new flipper power.