Rambam: Keilim, Chapter 8

The Alter Rebbe rules (33:6) that there are debates about this. Some say that they cannot be repaired at all. Some say that if the tear leaving enough material to wrap around the arm once and then reach the middle finger and wrap around it three times, then it can be tied back together. Others say that if enough material was left just to wrap once around the arm, it can be tied. The Alter Rebbe writes that one should be strict and follow the first opinion, unless it is impossible to procure new straps.

New straps are not very expensive. I would recommend getting new ones if you can. Reply