Quoted from sethbenjamin:
You'll be fine! Work methodically, soberly, and not in a hurry. Get help removing the playfield and reinstalling it.
Once it's out, you'll be able to look at things and understand them better than you did before. And you'll be able to clean off a lot of stuff that is dirty, as well as replace parts you didn't notice were broken or missing, and tighten things you didn't realize were loose. If you take advantage of having your playfield out and spend a few days tuning it up, you'll be amazed at how much more fun your old game is. A lot of people think that pinball used to be less exciting in the 80s, because they play games at arcades where the older games have never been properly shopped in decades, sitting alongside new Sterns and JJs that came off the assembly line a few months ago. (I'm looking at YOU, Pinball Wizard, up there in New Hampshire )
You may want to read Vid's guides to flipper rebuilding and pop bumper rebuilding. They're essential to getting your game to play the way it's meant to.
Also, don't forget to remove and clean the ball trough parts, and replace the balls! They get gross with age. Smooth metal parts mean clean, undamaged pinballs and less wear and faster play.
Thank you sir!