[T2] rear brake light question

[Kevin S. Clarke]

My left rear brake light stopped working.  I confirmed it wasn't the bulb
and then started tracking down the wires and grounds.  I learned the
positive wire that goes to the left light comes from the right rear light.
 That right rear light has two contact points (as does the left).  One
contact point on the right is connected to the incoming positive wire and
the other side has the positive wire that runs from the right light to the
left light.

When I put both those wires (incoming positive and outgoing positive) on
one side (contact point) both lights work (right and left), but when I have
the outgoing (to the left) on the second contact point and the incoming (to
the right) on the first contact point only the right light works.  It seems
like this means it's not getting enough current to make it through the
bulb(?)  The bulb is new.  Is my understanding correct (I'm a newbie) and,
if it is, where should I be looking next?

Thanks,
Kevin