Lorel - 6:39 pm on Mar 5, 2013 (gmt 0)
I often run Zenu to check for broken links on my site and there aren't any. I have custom 404 and 410 error pages set up already (and they are working) and I list the most important pages on the error page so I don't loose anyone, but Google apparently records the errors anyway.
I haven't found a valid reason to set up a redirect for the errors I see as they are mostly typos, like someone adding a "/" on the end of .html -- which is caused by not hitting the enter key or other dumb errors/typos.
I just mark them as "fixed" and in about a week my traffic starts climbing again.
They are all unique errors too -- typos -- not indicative of a navigation problem. I've even typed a url wrong and found it in Gwmt later.
I haven't checked to see if the page's rank was affected yet. -- next research project.