Those two switches are daisy chained together & then to the 6 blue/green targets on the left side.
The white wire with a yellow band connects from MPU-J2 pin 4 to the lagoon saucer, cave saucer & then to the targets.
First I would check for a physical break in the white/yellow cave wiring near the playfield edge - these wires get caught & damaged on the edge of the playfield when you raise/lower the playfield. Follow the two white/yellow wires from the lug till it clears & goes into the loom. On my game these exact white/yellow wires have had the insulation scraped through from this.
Assuming the 6 drop targets are registering individually (not just the bank resetting) then it's not a MPU-J2 pin 4 connection problem, check continuity between the white/yellow common wire on the targets to the lagoon/cave white/yellow connection & also continuity between both lagoon & cave trap to MPU-J2 pin 4.
Check their are two white/yellow wires connected to one lug on both the cave & lagoon switch.