Rectifier / Regulator Testing For Dummies

I couldn't figure any of this out so I researched it on YouTube and this is the definitive video of how these bits of kit work and how to test them:

I set up my own test and tested the rectifier off my Dad's bike (which I assumed was OK since it was working 10 years ago) and my Road Runner bike which is not charging it's battery.  Both of these rectifiers has a red and black leads and 3 other leads which are the loads. (click to enlarge)

These tests proved that my Road Runner rectifier is toast.  On 2 of the phases there is no current flow in either direction.  This is consistent with these 2 diodes being burned out and thus breaking the circuit.  It is also possible for diodes to break down and allow a voltage drop in both directions.  That would be a fail too.

It also shows that there is a problem with one; the number 3 diode on my Dad's bike as the ground circuit no. 3 diode does not allow a circuit in either direction.

2 new rectifiers are needed.