Disappearing Google Search Engine

My google search engine in the sidebar sometimes disappears, although when it is there, it seems to work. When it disappears from the side bar, an icon remains. When I click on the icon, the code for the search engine shows, but I don't know what to do about it.

I also had the search engine as an element in an older post - although it was there for a long time, it recently disappeared completely, and I don't know why. There is no icon left on that blog post.

You may also see my google search engine on NonHuman Primate Morality on my website. So far, it has remained there, but I am a little concerned about it. Some people seem to include the entire search engine page, which shows favored sites, but mine only includes the actual engine.