I’m having a problem with my RW transformer.  There is no power to the variable terminal posts (A & B).  The fixed terminal posts register their specified current on my volt meter.  When the whistle control button is depressed both variable terminal post (A&B) register the required electrical current.  This is while the transformer is plugged into the wall power.
The circuit breaker tested good on both terminal posts (A & B). 
The wire connected to the voltage control lever/arm and the terminal post “A & B” register continuity. So that’s good.
The slider contacts on the whistle control assembly had just been cleaned and appear to be working correctly.
I’m stumped!  Does anybody have any suggestions to the problem or a fix?