there is a paper index (held by Manx Museum tho I have a copy) of all those on the 13 reels filmed presentments 1658- 1768 - you can derive some form of index to the 1630-1699 presentments on Arch wills from J M Oates index - the episcopal films which were indexed over a decade or so ignored the many interesting church court records though it would be possible to derive the position on the film by looking for the gaps in the frame numbers of wills (however since filming the museum (or possibly the Rolls office) has 'misplaced' at least one important set of such records which would seem to imply they were separated from the will books)