You could try the 'Butkus Camera Manual' site (recommended),
or contact Vivitar directly, (good luck with that).

http://www.butkus.org/chinon/vivitar...lash_units.htm

Email: support@vivitar.com
Contact or call Vivitar at: 805-988-0463
Phone:
US:
1-800-592-9541
UK: 0-800-917-4831
Australia: 1-800-006-614