Periodically I get customers who want to send me a tallit for repair work on the tzitzit. Bad idea! The last time someone did that Israel Customs decided to charge NIS 131 and it dragged on for weeks.
And in his case it was a much more complicated tying custom (Chabad) and he had to do all four corners, whereas in most cases there’s just have one corner to replace. In the time it takes you to stand in line at the post office, you could get the job done.
Some tzitzit tying posts make it sound more complicated than it really is. Let me put it in very basic terms. For any given corner you take four tzitzit strings. Three of them will be a regular length and one will be longer. (A standard package of tzitzit strings comes with 12 regular length and four long strings.)
Then just before you insert them into the hole you say לשם מצוות ציצית (“lesheim mitzvas tzitzis“). You even them up on both sides and tie a double knot. Try to make it so the double knot touches the edge of the tallit, without scrunching it up.
So far, nothing to it.
Then you take the long string and wind it around the others seven times. (About three minutes of work.) Tie a double knot.
That’s really all there is to it. Afterwards you just repeat the windings and the double knot three times.
The only difference is the first time you count 7 windings, the second time 8, the third time 11 and the fourth time 13.
It should take you a total of 15 minutes, and it’s always best to do mitzvahs yourself.
You might even enjoy it! I no longer tie all our tzitzit myself, but I tie several times a week, usually in the evening, and I find it’s a really great way to unwind (forgive the pun).