There isn't an easiest way.
Take trap door off top of playfield, 2 clips 2 springs, have spares for when you lose them. I put a magnet nearby to catch them if/when they take off.
Under playfield disconnect connectors, 5 screws, lower the whole assembly.
Now the fun begins. Take the assembly apart until you can get at the back of the character face. Remove two screws, swap character face. Then reassemble. Then spend the next hour or two getting the whole shebang to go up and down smoothly. Lots of loosening, adjusting, tightening. I found that holding the whole frame,screws lightly loose, squeeze frame together from all four sides, then tighten the screws sometimes works best.
Stick it back in the game in reverse order you took it out in.
Only three more to go.
LTG : )