To fix a leak at the yoke connection, ensure that your plumbing is not putting too much upward or downward pressure on the yoke connection.
Next, check the 4 o-rings found within the yoke connection, located on the two couplings that seal the yoke to the bypass. Ensure these o-rings are in the grooves and not pinched. If pinched, they need to be replaced.
Next, ensure that 8-12 wraps of Teflon tape have been applied to the yoke threads and your plumbing.