I've had to correct mis-rigged Bahia reefing lines recently, so I thought I'd explain how to rig the line properly. You'll have to do this if the main sail is crunched at the leech when you raise it fullly or if you can't fully reef the sail.

It's a little confusing, as it's two lines in a "jiffy reef" system, so that you only have to pull on one line to pull down both the luff and the leach of the sail. But once you get the picture, it isn't that hard to deal with. Here's what it looks like:

The line through the leech of the sail attaches to a block in the boom. The line through the luff of the sail runs through the block and back out the forward end of the boom through the cleat.

So what happens when you reef is this. You pull on the line at the forward end of the boom. This pulls the block attached to the leach line forward through the boom, pulling the aft reefing line down and raising the boom to the reefing gromet. You get here:

At this point, the block is as far forward as it can be in the boom, so pulling more on the reefing line pulls the luff reefing line down to the boom (you ease the halyard as you do this). So you get to here:

The boom should be 90 degrees to the mast, and you're done (except for cleaning up the lines).

But what about rigging or fixing the reefing line?

I'll skip how you pull the block through the boom if you have no lines at all. It isn't that hard - you use a fish line, and it's easy because both ends of the boom are open.

Let's assume that the lines are more or less rigged, but that they aren't working. Either you get a crunched leech with a full main and the reefing line loose or the boom doesn't come up enough when you try to reef. Either of these says that one of the reefing lines is not the right length.The procedure for diagnosing this and fixing it is pretty simple.

On land with the boat on the trailer and support under the stern (a cooler with a life vest or two on top of it) and the boat pointed dead into the wind, raise the main fully with the reefing line completely loose. 

Here's the procedure:

1. Make sure the sail lug is aft of the reefing line loop around boom.
2. Pull the block inside of the boom all the way aft by pulling the leech reefing line
from the boom. If you cannot do this, or if doing it crunches the sail luff, the luff
reefing line is too short and should be replaced.
3. Pull on the reefing line coming out of the boom so that the line through the luff is
just a little loose, cut off the excess, and put a stopper at the end of the line (plastic ball).
4. If necessary, untie the loop around the aft of the boom and retie it so that the line
through the leech is just a little loose and cut off any excess. If you cannot do this
(i.e., the leech stays crunched), the leech reefing line is too short and should be replaced.

Here's the diagram:

Finally test it by pulling in on the reefing line. It should pull the reefing clew to the boom.
If you followed the above procedure, it should work the first time.