I have a 2015 zforce 800ex. Out and about this weekend I pushed the 4x4 button and the machine would not go into 4x4 mode. Hi or low. The display never would switch to the "X" icon. when I turn the key on I see the displays show the X, so at least I know that is there. I have owned this sxs for a few years and my wife loves it! It is hers. I have noticed over time it would take longer and longer to engage. I am not new to the scene and have been in the sport for close to ten years. I ride ATV's but the wife likes the cage. I am looking for suggestions to where to start troubleshooting this problem. Thank you in advance for the help.  I have found with the CFMOTO's anything before 2016 is hard to find parts.

[2015 Z Force 800 53/Trail EPS]

I would pull the actuator..which is a bit of a PITA, and work it to see if what..if anything..it does. You can check the fork-drive slide for smoothness and operation while in there and you can test the power leads to the motor. If it is used a lot...and it sounds like it may be, the motors and drive gears may be having a problem. You can open the actuator up and check/clean the drive gears and test the motor. Overall, if the fork slide is good and it is getting power from the switch...and many have had failed switches...it's likely time to replace the actuator..IMO. Once open you will see this:

Yes, they look just like that.
I had a simlar issue with my 22 800XC.
Figured out that the gear oil had flooded the actuator case where resides a tiny little electric motor.
Sad part is, it's a 50 cent motor. You can find the motor.
But I have yet to find one with the right shaft length and tooth count on the gear.
I do do a lot of Up and downhill. Somtimes steep enough I have to lay back and have my feet on the fender well portion of my running boards to keep from flipping over the bars.
But, the seal shouldnt have failed either.
I ride the heck out of them, but really don't pound on them.

The positive side is that so far, the overall machines are actually rather pleasant to work on once you get to know them.