Try this site:
http://s2.vsmgroup.com/VSM/Pfaff/pfaffmanual.nsf
You have to scroll down to Pfaff 1212 and click the link, then scroll down the page again to Pfaff 1212 and click English and then scroll down again and click on Manual. It's a lot of scrolling but you'll get there.
Pfaffs from that era are nice machines but be warned they do have a number of plastic parts and a broken camstack renders them almost useless---might straight stitch, I'm not sure. Even the screw that holds on the balance wheel is plastic although you can still get those. Don't over tighten it when you put it back on or it will break.
Similar machines will be the 1189, 1209 and a couple of others. It's a "lesser" version of the 1221 or 1222, probably. It should have the walking foot which is a very nice feature.
Good luck.