Exactly what the title asks. How do I clear xmodmap settings?

I have an IBM model M, and somehow xkeycaps got it into its head that my "End" key was not any key at all. xev reports keypresses when I use it, so I know the event is being generated by the keyboard. Also, xkeycaps thinks that my arrow keys are all wonky, and apparently the scrollbar is broken so it only scrolls down - so I can't scroll up to find an IBM keyboard that just maybe is close to my map so I can fix my keys.

So I'm trying to reset my keyboard to the default settings, but the xmodmap manpage is woefully devoid of "reset all" or "clear all" or anything of that nature (that I was able to find).

Help would be greatly appreciated!