Just got a new MCX tandem and control test function as described in the manual, but helicopter is not stable at all. I have adjusted trims to the max and heli spins to right and backwards no matter what I do. I have to hold rudder full right and elevator to attempt to fly straight. Any ideas or suggestions. Forgive me I'm just a newbie. I am using a DX5e radio and have no problems with my other MCX2 or MCX original.

a little confused with your post. you said the heli spins right and you hold right to keep it straight???
you may have the rudder channel reversed on you radio for this model??
i have a mcx tandem, but with the eflight radio.

Meant to say full left rudder. Fingers typing faster than my mind works.

If it is not in the book I would call e-flight and ask what the dip switch settings are. Had the same type problem with the same radio when I went from my CX2 to mCX. Good luck, it's a fun little bird. Make sure you check the linkages after every strike or hard set down. They tend to pop off a lot but are a 1 second fix, since they don't usually fly off, just hang from 1 ball link....

If the MCX and MCX2 fly OK with your DX5e, then its dip switches are set correctly. All 3 of those birds use the same setttings on the DX5e. I suggest that you rebind to the transmitter. It is easy to do it wrong. It is also easy to inadvertently hit the trainer switch and loose bind. Been there, did both. Another thing to check would be both swashplates. One may be separated.