Greetings,
My 2020 800XC machines continue to give me problems (battery, starter, sprague gear, gauges, ignition.....).  Now it's the cam chain tensioner.
I would appreciate any info/suggestions as to why the plunger on the chain tensioner melted.  It was leaking oil, so I removed it; only to discover the plunger was melted ("welded"). 
Thank you.  Stay safe

[2015 Z Force 800 53/Trail EPS]

Because CFM doesn't use a ratcheting-type tensioner, only a spring and plunger type, as the back side of the chains wave with play so does the plungers move in the housing. This and a combination of the spring loosing its resistance to this action causes excess heat and in some cases the melting of parts. DO replace all effected parts and be sure to replace the spring as it is the #1 cause of this movement when it starts getting weak. They really need to go to a ratcheting type like Kawasaki did many years ago.