Yeah, that statement is confusing - "The power from one ZW runs to variable input 1 and the power from the variable input 2 on the TIU." I assume what you meant to say was that power from one ZW goes to variable input 1 and power from the other ZW goes to variable input 2 ?
A couple of things to try and narrow things down - disconnect one ZW and only run one ZW to one variable input and see if the problem persists. Then use the other variable input with the same transformer. Then swap the ZW's around and see what happens.
Do you have any non-convention (command) trains to run ? if so, try running one ZW to Fixed input 1 and swap them around to see if the Fixed inputs work.
Also, are these separate tracks/loops that each output is running to ?
