I have a rotostay Mk2 and don't do anything on an annual basis, but abt every 5 years I strip it down completely and replace what is needed through <A target="_blank" HREF=http://www.xwrigging.co.uk>http://www.xwrigging.co.uk</A> Mine is 20 years old and working as well as the day it was new. The five year cycle co-incides every other service with a replacement forestay. The important point is to ensure that the push fit joint of the foil to the drum is very well greased and that the top of the foil is capped with a rubber bung and some silicone.
I am in the market for another S/H mk2 if you have one!