Quoted from Pinball4life:....
An obvious tip for newbies, and for people like me who are not so mechanically inclined....I require all my guys including myself to "map" a game as you are taking it apart. We take photos of everything, then print them out and code all the parts. Then, it's quite easy to reassemble just about any game! Been at it 35 years and this is by far the best system I have come up with. Also, other people can jump in if another was in the middle of a shop job. Get a few plastic boxes with bins with dividers and label on the printout sheet where you placed the hardware (iD each bin of course). When we unplug the connectors we use different color labels for wach one. Do these steps correctly, and write good notes on the photo pages, and you should have few problems. Even new people can come in here and correctly reassemble a game after going through just one pinball with someone that is trained. I'm sure there may be better ways but the extra time is worth it and I haven't discovered anything better.
^^ +1
I use the "Take two pictures of every step you make ..." (even if it seems sooo obvious, it makes all the difference later) put everything separated in a box which has many compartiments. Descibe every step you make in one line.
Putting things together read the desciptions and watch the pics in reverse order.
STTNG, WH2O and TZ beeing proposed as hard... on WH2O and STTNG definatly the numbers 1 and 2 (for me...)