Here's my advice:
Get a bottle of 91% Isopropyl Rubbing alcohol, a bottle of Novus 2 plastic polish, and a can of Pure Carnauba Paste car wax.
Clean everything with a soft rag and some Isopropyl Rubbing alcohol - cuts dirt and grease without damaging the playfield.
Especially clean the plastic ramps and any plastic subways under the playfield - they hold tremendous amounts of dirt.
Then use some Novus 2 polish and a clean rag to really clean and buff the hell out of the playfield.
Then use some of the car wax to put 2-3 coats of wax on the playfield, just like waxing a car.
Buy brand new pinballs:
Premium Ultra-Gloss Pinball
Price: $1.50
Product ID: ooohhh_shiiiiny
http://www.pinballlife.com/index.php?p=product&id=1325&parent=0
And the Big Tub of white pinball rubber:
125-Piece White Rubber Ring Set
Price: $27.95
Product ID: 125_white_set
http://www.pinballlife.com/index.php?p=product&id=486&parent=0
And change out all of the rubber you possibly can, including the flipper rubber and shooter rod tip. There is enough rubber in that tub to do 2 or 3 pinball machines, at least.
New white bouncy rubber, a clean and waxed playfield and new balls will bring a game to new life - amazing fast and responsive.
Also, level the game properly - I use an iPod with a (free!!!) level app to get the playfield dead level side-to-side, and get the correct slope of about 6.5-7.0 degrees.
Get your game clean, waxed, rubbered and dialed in and you will love how it plays.
Night and day, believe me.
RussMyers