Repin those pesky connectors! Honestly, for an evening of work or a couple of days depending on your experience level, is one of the best investments in getting a machine to work reliably.

As far as having multiple solenoids fail, usually this is one of several things. The power is daisy chained from one solenoids to the next, so one broken wire or solder joint can cause all of those downstream to fail. Check both sides of solenoid fuses, including any under playfield fuses, for DC solenoid power using a DMM.

Those are some starting to points, if you get stuck post some more details and we'll all try to help out.