Wow - too many problems happening at once here,
1. Solenoids first. They work with the special solenoid circuit - top left connector on driver board. On the bumpers there are two switches. the one on the spoon does the firing, The lower - furthest from the pf is for scoring which is via the switch matrix. Is vibration causing the adjacent solenoid to fire - visually examine the spoon switch gaps. Stick a piece of paper between the adjacent ones to test if it's vibration. You can also disconnect the playfiled plug at the driver board and test directly to the driver board pin.
2. Switch matrix. Did you verify normal operation of the driver board without the playfield connected as suggested?
Note the upper right standup is in a different col. If the driver works on its own then look very carefully over the 3 bank drop setup as this is common to the col. You can easily undo and remove the three drop target circuit boards for examination.
I'm not convinced that replacinging diodes will help at this stage - for it to be a faulty diode two things must simultaneously occur; firstly the diode must fail closed and secondly the corresponding switch must be closed .... lotto time?
