Sorry to resurrect a very old thread but I was having the same issue on my machine, higher power wasn't doing anything the ball would just sit at the bottom and not move up the playfield at all.

But I took the lazy mans way out after reading this post. I took a pair of side cutters and some needle nosed pliers and very carefully snipped the white nylon washer and pulled it away with the pliers. Now the mini playfield moves the ball up and down, what a wonderful post. Thank you soooo much