Issue: In all modern pinball machines (WMS/Bally), the use of LED's usually leads to ghosting, a condition where other LEDs also are lit or flickering while they shouldn't be.
Solution: While there are special non-ghosting LEDs out there, these are expensive and just not needed. The issue stems from a timing problem within the lamp driver code when using LED's instead of conventional light bulbs.
Luckily there's an easy fix - and its called WPCLP (WPC Lamp Patcher), and was kindly made available on GitHub by Eric Conner, programmed by John Honeycutt - https://github.com/EricConnerApps/wpclp/
This utility basically takes an existing WMS/Bally WPC ROM and modifies the lamp driver code to behave with modern LED's. If you want to try it for yourselves, pull a copy off of github, compile on your favorite platform (i'm using gcc but mingw should work just fine) and give it a spin.
Here's a quick snap of it in action:
Take that patched ROM file (in that case a T2), burn it, and you are good to go. If you don't want to do the work, feel free to contact me for any EPROM needs you might have.