Have you contacted Sailomat? They're still in business and might be able to reproduce a manual for you.
Design Office and Factory-Direct International Sales
San Diego, California, USA
A google search turned up a 13 month old thread on the Cruisers' Forum where a fellow named Peter Schellekens said he had a complete manual and was offering to help another fellow who needed it. You could also try contacting him. You can find that thread here
T. P. Donnelly
S/V Tranquility Base
1984 Islander 30 Bahama