Roland SH-2000, only some waveforms working

Hi folks,

I’m at a bit of a loose end at the moment so I’m looking ta a roland sh-2000 which only has a few voices working - I signal traced and the signal gets lost at the s6/s6/s7 part. Int he schematic you can see it circles at the top. The signal is there at the 1m resistor point, but then gets super quiet at the diode and 100k resistor point, which is where the signal leaves the wave board to go to the motherboard.

Something I’ve noticed which is a bit weird (or maybe just me finding a pattern where there is no pattern) is the signals that are working all use a bunch of diodes, and only one that uses a bunch of resistors works? As shown in the schematic using the red and green. Also the voltages seem to show differently on the working signals with one weird one (I can post a table for this if needed). Voltages all seem the be find coming from the divider chip just something happens along the way.

Unfortunately Im stuck checking this with the components facing down as that’s how the board fits into the motherboard.

Any advice on what I could chekc next?