Posting this in general as I'm suspect the button on my 2019 uforce 800 is the same as other machines- didn't want to get buried in the sub firms. Hope that is ok.

Red button- 2wd/4wd works fine. When i move the lever over and try to press the yellow diff lock button, it never pops out/engages the diff lock. Just stays in 4wd reg.

Any ideas to trouble shoot this or how to pull that section of dash apart to get at the button to see if something is making it stick?  The copy of the service manual I have doesn't show anything on this.

Thanks.

[2015 Z Force 800 53/Trail EPS]

There has been lots of issues with that switch system. I even have had some with mine that got solved with lots of spray contact cleaner forced into the buttons...and the lever because it always gets stuck on me more often then the buttons not making contact. Not 100% sure on how to get them out but there is two..(I believe) ..retainer bolts that you have to get to on the back side. Interestingly that setup is very much like the Yamaha Rhino's and others Yamaha puts them of...which never have issues like the CFM's. I think when I have to replace mine I will wire-in a Yamaha instead.

Try the contact cleaner first..don't use anything like WD-40.