I went over to a 750 sport Forum and while looking I found a link for the Correct manual so now very happy ?paso and 750 sport will also have weber info in the manuals - it probably tells you to take it to a weber specialist. you really won't get anything of use out of the manual in that regard. the paso forum is the best place for finding info about playing with the weber - some of the paso guys are real nuts.
there's a few of the 90 in australia. while it's officially a 1990 model, i believe most of them were built in early/mid 89 at the old morini factory. if they'd waited for the 1990 updates to the paso bottom end it'd have a normal clutch set up.