One of the knots on my tallis gadol came undone, leaving me with 4 double knots on one side instead of 5. Is the tallis still kosher or must I have the knot redone?
You should have the fifth knot redone. you most probably will be able to find the string that goes around the knots. Seperate the two sets of four strings, and find which string is the long one, that goes around the rest. Make a bow out of the set of four strings from the set that doesn’t have the long string as part of it. This is in order to keep track of the two sets of strings If you are Ashkenazi, then the long string has to now go around all the other strings 13 times. After you have done that, take each set of four strings and make two knots. Then you are done. Just make sure before you start that you say, that you are doing this “l’sheim mitzvas tzitzis” for the mitzva of tzitzis.