If you lack any skills like soldering or using a meter, Youtube has lots of short how to videos.

Auto Launcher - check coil sleeve for dirt, wear, cracks, replace. Clean plunger. Check for loose or worn parts.

Flippers - I'd rebuild and start fresh. New coil sleeve, new coil stop, new plunger assembly.

Ball getting back to playfield - check for dirty or worn parts. Make sure switch in there is working. You game has a switch test - go into it and hit some switches so you learn what happens and what reports on DMD.

vid1900 has a good write up here on Pinside to rebuild flippers. You can search posts on cleaning and waxing your playfield. If you order any parts, I'd add some new balls for your game too.

Leveling game - Todd Andersen has some useful articles on Pinball News :

http://www.pinballnews.com/learn/level/index.html
http://www.pinballnews.com/learn/iphone2/index.html
http://www.pinballnews.com/learn/iphone/index.html

And when you run into a problem. Don't get frustrated. Post here, pictures too if needed. And you'll likely get some help.

Welcome my friend, to the wonderful world of pinball.

LTG : )

I'd check the manual, high voltage ones 50V ( might be higher not under load ) I don't know if Stern used and low power coils in that game.

I'd carefully check the wall outlet AC and then check what the game is wired for. And example of wall outlet 100AC and game wired for 120AC will give you weak coils.

Don't wire the game lower to make things stronger. Just try and match the voltages.

LTG : )