LEDs - Don't!
All,
When changing stuff like this, it is important to understand that color is secondary to the original design function and failure modes.
The use of LED lamps in legacy pinball machines is a risk to your machine.
LEDs have a different failure mode from an incandescent lamp. Most LEDs have a rectifier in the lamp base - rectifiers can fail open, or DEAD SHORT TO GROUND. Normal lamps just fail open, with few, relatively rare exceptions.
If the rectifier fails by Dead Short, it will at a minimum, blow the driver chip out. At a maximum (if the driver doesn't blow out), it can blow traces right off the board. Since these connections aren't individually fused, the normal fuse that feeds the board is too big (since it covers the entire output) to go, before damage occurs.
This is the voice of experience here - we had a very expensive board on an analog control system get traces blown off it when the LED rectifier failed to ground. Be careful - and the older your pinball, the more careful you need to be. It doesn't take much to burn the cloth insulation of the wires in these games.