Hi , There will be a serial # either on the chassis/sub frame ,or back (if later model)Have a gander at these sites --they have answers to most Linnie queries.
http://www.pfmedia.demon.co.uk/flatearth/lp12.htm
http://www.mana.co.uk/menu.htm
http://www.geocities.com/Hollywood/Hills/4133/lp12_faq.txt
Best,
Des