I have done my best to search the Forum to see if this info has been posted, so please excuse me if it is a repost.
Signet Address: requested on http://www.vinylengine.com/library/Signet.shtml
Marketing address: 4703 Hudson Drive, Stow, Ohio, 44224
The zip code has probably changed.
This is the address in the manual.
My late 1980's Signet AM30S came with a signed (by stamp) undated strip chart record, and an Individual Inspection Report with Japanese red chops and a final stamped signature, but no serial number written in. So who knows if it was just good artwork or if it was really tested. I've gotten very good results with it. Manual was printed in Japan, but there is no address in Japan.