Jean,
Pickups do fail, even Alembic units, although rarely. Sending the pickup to Alembic will assure you of its condition. Keeping the other working pickup in the bass will at least keep you up and playing. As advised try moving the connectors while tapping on the problem pickup with a metal screwdriver to see if the issue might be with the external wiring between the pickup output and where it connects to the EQ circuit. Exercise the pan pot many rotations, too.