[A horse with no name]

Hi...Has that side of your front end dropped by any chance?..If so, the spline at the other end has been pulled out...If not, yes, it should slide/tap back in without any trouble whatsoever...If by chance that it doesn't, then you will have to remove the steel protection plate to get at the other end... Jacking it up would make it both easier to tap back in, including of course to work on.

Re the end cap...You should also be able to be just tap it back in. It's just a friction fit, so you may need to use a punch on a few points along its edge to expand it so that it doesn't fall out/off.