I did a web search for you but couldn't find a link to a manual. I did however find sites where others were asking the same thing, so they must be a bit elusive. .

After looking at several sites, the common concensus seems to be that you should contact the company that made the chair, quoting the chair's serial number, and hopefully they'll be able to provide you with a manual.

Here's a website that actually gives you a phone number to call, but I don't know what state that is.
http://www.fixya.com/support/t189241...overound_mpv_4