The turn signals have independent hot wires, they are not dependent on the rest of the cluster logic. The right turn signal is on B14, so if B was disconnected, that light would stop working no matter what.

I would not rule out B5 quite yet, but I would not stop tracing out B7.

another possibility is that the solder joints on the back side of the B connector may have a problem as well. You may want to reflow the solder on that connector if you have the tools to do so.