1. why to use a Y harness on a 9ch digi radio?
2. try to check the 2 ele servos on different channel such as alie - see what happenes and vise versa - get te 2 alie servos and put them on the elev ch.
3. do he same on a different working rx with a differernt model setup,( a reset one) on the radio.

u need to find the rootcouse first.

good luck