I think this post probably should be in rubber-side down, but if I get the answer then it will help others with little/no mechanical knowledge like myself

when they find this thread.
I get why we do this check, but I don't seem to have found anything in this thread that tells a newbie like myself, what to do to fix the problems.
I mean if the chain is stretched I assume that obviously means replace cam-chain if passed the maximum stretch point.
And if the arm the plunger goes into has become (I think the term used was oblongated) through misaligned plunging, then a new arm is needed.
Am I correct here?
At 17822km on the clock I should check (I bought at 13000km) and without having any knowledge of what has been done mechanically before, it is a sure bet the plunger is not far off popping out of the arm.
I just don't want to check it only to find myself wondering 'ok it's almost farked...so now what?'