[drh4683]

400 color remotes are probably the hardest to find of any space command remote. There have been numerous 400 color sets that show up, and not one of them has ever had the original remote with it. I was fortunate enough to have found a 400 color remote on ebay about 3 years ago. I think the reason they are so hard to find is because those first generation oval button remotes, like the 400 used a different mechanical hammer mechanisem. If you look at an early remote, the oval buttons are angled downward tward the front of the remote and have more ivory colored buttons. Those remotes used a plastic pawl to load the hammer spring. Ive seen so many of those broken, and the button wont work, and or gets jammed and stuck on an angle when you push it down.
That being said, I would think alot of those remotes got replaced with space command 600's (from TV shops I suppose) as it was a better remote from a mechanical point of view. Just to note, early space command 600's were the same way, so I think remotes from 1966 or later are the "better" design and you seem to find them with the sets still and "working".