I looked around the forums and there were some posts about filing down the existing magnet core if it gets worn (instead of replacing it) and another mentioning to take the screws out to remove the entire assembly to adjust the core. Personally I didn't want to take wood screws out of my playfield to remove the whole magnet assembly if not necessary. I could see that all I really needed to do to adjust it was loosen that big ole nut that clamps the core down so it can't wiggle. Once its loose you can easily adjust the actual core up or down to make it flush with the playfield.

Didn't find anyone anywhere mention the size of that nut though. I measured it best I could and came up with 1" 1/16th. Had to go get a new socket because my socket set only goes up to 1". Got home and found out it is actually a 1 1/8" socket that you need. Anyways, adjusting it worked out fine and stopped my balls from getting stuck because the magnet was initially too low in my machine and created a crater for the ball to sit in. Hope this helps someone else not waste two trips to Home Depot to figure out which socket size it is. Of course you could also use an adjustable wrench but it seemed safer for the surrounding wire harnesses to use a socket instead...

BTW, since I did all this research the nut is a 3/4-16 HEX JAM NUT. Part #4428-01135-00 but it's just a standard nut you could probably find at Home Depot instead of buying it from a specialty shop.

Good luck. Hope this helps someone else save some time.