Since no one else has yet replied, I'll offer some suggestions until someone more experienced responds.
First, it helps if you describe what the issue with the handles is that you are trying to fix. Is the locking mechanism sloppy, is the handle mounting mechanism falling off the door, or is the handle itself broken?
Also, can you describe the style (or better yet, post a picture) of the handle. Although Eichler used almost exclusively Arcadia doors, the models and details changed by tract and era. (For instance, the 1960 Fairglen Eichler I live in has aluminum doors and the Palo Alto ones I've seen were steel.)
With the above information, fellow Eichler owners on this web board can either offer parts or advice. Failing that, I recall there was someone advertising in the 2007 Eichler Network Home Maintenance Directory (I think he's listed under general contracting siding repair but he does all sort of door and exterior repairs, including sliding door repair). If you can't find his contact info, let me know and I'll email you direct.
There are numerous posts on the subject of latches/locks for Arcadia doors, where you can buy replacement products, and information on local companies that can also do repairs.