Quoted from thedefog:if you're gonna stock up on diodes, just buy 1n4007's. They're rated at 1000v, and can be used anywhere.
Very good info. I wasn't aware of this.
Bradleehall you are on the right track in thinking you need to start at the end and work your way back. Look at the wire matrix in your manual and see what color wire all the switches involved share. Make note of this. Are all of the switches that share this wire not working? If not then you can start at the working switch and physically work your way from there. Go to that switch and follow the shared wire to the next switch. You will have to actually get under the playfield and follow that wire to the next switch. If I didn't find any shorts (breaks, loose connections, naked spots) I'd unsolder that wire from the switch you just traced to. It should be the one you just followed up and another one, same color, that goes on to the next switch. Remove those from this switch and connect them together. Then retest the switches except of course the one you just took out of the line.
If none of the switches are working that share the same row/column then you will still have to get under the play field. Find the wire color you are looking for. Even better if you know where this wire comes off the board shake this group of wires at the back box while looking/feeling for it under the playfield. Find you color wire in that bunch. Follow it to the first switch it comes to. Then to the next and so on until it finally ends. Make notes of their order. Compare this to the book. If the order isn't the same as in the book make numbered notes I the matrix with PENCIL. Now you know for sure the order. Eliminate each switch from the last to the first in the same way I described above this should at least let you isolate the problem down to which switch you are having the issue.
Its not as much work as it sounds like. The jumper test works too. Unplug the plug from the board that contains the affected wire. Put and alligator clip to the pin of the suspect wire. To make sure it isn't touching other pins I fold a piece of paper, put it around the pin I want to clip to, I clip to it in a way that the paper is around the alligator clip keeping it from touching other pins. Next go to the switches one by one. Remove the suspect wire and now connect the other side of your jumper wire to where the suspect wire went. Go into test mode and test the switch. If it works, power the game off, reconnect at the switch and move to the next and repeat.
Order those diodes in case you haven't already. If the above doesn't work replace all the diodes on the switches in the affected row/column. If that don't work replace the switches. Its cheap. This is probably going to boil dow to being a really simple fix. Hopefully we find it soon.
Report back on what you've tried and what happened. Good luck.
Here's the topic I started on here in case you're interested in a good read.
https://pinside.com/pinball/forum/topic/bride-of-pinbot-bop-sw-67-location