Not sure quite what kind of rig it is, but if you're unfurling it without touching the halyard, then it must be roller-furling into the mast. This must be why they don't want you changing the halyard tension, because it affects turntables at both ends of the luff.
If so, and you've got too much draft (depth in mid-sail), you can try tightening the foot with the outhaul control. If you want to flatten the draft still more, look for a cunningham cringle, a ring on the luff about a foot above the tack. Run a line up to it or through it, then to either a tackle or a winch, and crank it down to give you more luff tension, and hence less draft (and will pull the existing draft more forward).
If the main doesn't have any of those controls, or it's still too baggy, then it may just be blown out with age. The cure then is a recut or a new main.
I'm not a big fan of roller furling mainsails, I like battens and the stability they give the leech.
Last edited by nolatom; 09-08-2006 at 03:10 PM.