Congrats on the your first pin. I agree with Steve and start with the connectors. Also check out this link

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Sound_Boards

It has trouble shooting tips for your sound board.

Edit: check out this as well. Same page just further down.

http://www.pinwiki.com/wiki/index.php?title=Gottlieb_System_80#Sound_problems

Wow... good price. Not the best looking pin made but for the price you got a good deal. Take a look at the links I gave you. It would be a good idea to read through the whole document. It has a lot of good information. If you get stuck be sure to ask more questions. There are a lot of helpful people on this site.

Nice job on getting the sound working. Your ball problem sounds like your out hole switch isn't working. Put your pin the switch test mode and make sure that switch works. If not check the switch and make sure its adjusted properly. Also check the wires and make sure one didn't break off. Tug on the wires gently and make sure they are solidly connected.

I don't have any System 80 games and don't know the menu system. But your manual should be able to tell you how to get to the test menus. In the test menus there should be a switch test. It will tell you what switches are closed. It will probably just show the switch numbers and you have to look in the manual to see what switch number your out hole is. When a ball goes into the out hole make sure the switch registers as closed in the switch test. If it doesn't then most likely it's not adjusted properly or one of the wires have come loose. Or it could be the switch is working fine and your coil isn't working. You can do the same type of thing and put it in coil test to test the kickout coil. If it doesn't work in the test then it probably has a loose wire. Your coil will be numbered similar to the switch and your manual will show which number is for your kickout coil.

Hopefully someone with a System 80 game can chime in and describe the menu system better. But it should all be in the manual on how to get into it.

Give a little tug on the wires to the sockets and make sure they have a good connection. Inspect the socket and see if it looks corroded or look like its falling apart. Clean the inside of the socket. They make a socket cleaner that looks like a very long pencil eraser that you can pick up at any pinball parts place. Its worth the dollar or two as a lot of sockets just need a quick cleaning. If you don't have one take some fine grit sandpaper and put it on the end of a pensil and twist it around the inside of the socket to clean it. If it still doesn't work check to make sure you are getting voltage to the socket with a MM. If voltage is good then you need to replace the socket. If voltage isn't good then you have a break in the wire somewhere that you will need to trace back.