I have a 135 jib/genny on my P10M. No matter what I do, I can't seem to stop sail leech from luffing.
It could be "blown." How old is it , how much service has it seen, and under what kinds of conditions? (Btw: Leeches don't luff.)
I have cranked down on the leech line, moved the cars, adjusted the jib main; nothing seems to work.
Start over. Ease the leech line. Now draw an imaginary line from the mid-point of the jib's luff, through its clew. That line will point to where you should start with your foresail cars. Then, under sail, examine your tell-tales. If the top ones flutter (in tandem) before the bottom ones, you have too much twist at the top of the sail. Move the cars forward. If the bottom ones flutter before the top ones, you have too little twist. Move the cars back.
If the tell-tales are all streaming aft pretty much equally, inside and out, top and bottom, and your leech is still fluttering, odds are the sail is a bit (?) blown. You should
be able to tighten-up the leech line a bit
to eliminate, or at least greatly reduce, the flutter. (Ragging on the leech line is probably counter-productive. If you close-off the leech too
much, you'll reduce the performance of the sail.)
We flew our 32 year old #3 (Dacron) Sunday and what I describe above was the procedure I used. (Tho that sail has only one set of tell-tales, so I adjusted the cars by sail shape.) No flutter. And yes: That trusty old #3 is definitely
a bit blown.
Btw: I suppose that by "jib main," you refer to the jib sheet(s) or jib halyard? There is no such thing as a "jib main."