The DATA 2 pair, pins 4 and 8 are SV-Network D-9 pin numbers. You need to look at the RV-12 Electrical diagram for your version of the electronics to trace the wiring for those pins through the AV5000. Typically labeled as EFIS DATA G (SV-Net, pin 8) and EFIS DATA H (SV-Net, pin 4) are signal paths you want to trace. The two servos are on different AV5000 connectors, so identify the one that is working and then trace the other connector/cable for the issue. Could be a pin/socket not seated, broken wire or swapped G and H wires. Use the wires in the Molex of the servo that is working as a reference.