rayelljay is right - too tight could cause that.

But is rudder action doing ANYTHING?? (Throttle trim all the way down..... apply full rudder and *slowly* throttle up...)

I assume you remember to unplug battery before adjusting set screws on the 4-in-1.
When I have to adjust 4-in-1 from scratch, I start with a mid setting on
both srews...

If all else fails then a systematic process of elimination should do the trick. Lucky for you that you have
working helis to compare tests to.

Good luck.