Chew the knot, it will loosen it up without breaking it apart.

It has worked for me on 2 or 3 knots.

wait til the next full moon, burn some special incense, chant some sanskrit knot-undoing prayers over the line, then roll it up around a freshly removed calf's horn, place it inside the cured skin of a large church cat, bury it under a willow tree and leave it for 40 days and 40 nights. when you dig it up all should be sorted. works for me every time. (this method is especially good when you have a spare lineset to use during the 40 days and nights).

or, you could soak it in warm soapy water before chewing on it or tapping it with a hammer to accelerate either process.

or you could search for any of the previous threads that have covered this topic in detail.