Showing redundant wirewrap connection for Sense Bit 14 entering the SBR card

WHY THIS REDUNDANT CONNECTION?

The wire around pin D10 of slot L3 is the one that carries the -Sense Bit 14 pulse from memory into the card that implements bits 14 and 15 of the Storage Buffer Register (SBR). Tracing the wire up to the pins for cable T4, we see that wire connects to L1 E11 which is -Sense Bit 14 coming from the memory compartment (or my 1130 MRAM board). All the sense bit lines from cable T4 are connected through the backplane to the pins of the card slot where they are implemented, including bit 14, so this wiring is redundant.

IS THIS A CLUE?

OR . . . There was a failure in this backplane causing some traces to become broken, which required the wire wrap to restore signal continuity. If this wirewrap connection became corroded at either end, it might lead to sporadic errors from vibration of the machine. I can check this theory by adding another wire between the pins. If the problem disappears with bit 14, I will have found wisps of gunsmoke, although not precisely the smoking gun itself.