As stated, find the problem why 30% of lights are out. It could be burnt connection, or perhaps just a fuse Also, if you have a manual (or download one), perhaps all the blown bulbs are on the same column which will help isolate the issue.

Personally, I will always leave incandescent in the GI, but I'm one of those that sees the crazy flickering/strobing. LEDs elsewhere may be useful. I just did a thread comparing LEDs, I was going for the not-super bright, more normal look - you can check that out here if you'd like: https://pinside.com/pinball/forum/topic/photo-comparison-comet-led-warm-white-options