The diodes D7 to D20 are all the diodes arranged as bridges that are used to get your different voltages for solenoids, flashers, feature lamps, optos, etc. Looks like someone did a wholesale replacement of all the diodes for some reason. If you are missing voltages or the fuses to the right of the diodes blow immediately at power up, then you have some issues with those diodes.

The diodes D25 to D32 were there originally for the GI lighting to convert the AC voltage to DC. The problem was the diodes burned up. The fix was to replace the diodes with jumpers or 0 ohm resistors. The diagonal wire is a jumper that effectively eliminates 2 diodes at once. That is a normal 'fix'.