I have several questions regarding the kashrut of tefilin... The top of my teflin shel yad ripped on 3/4 sides so that the inside of the tefilin was exposed. The top was glued back on, is this kosher? Also, the tefilin are very old hand-me-down tefilin. Therefore the hair that is supposed to protrude from the shel rosh is no longer really visible. I sent the tefilin to my rabbi to check out and was told that they were kosher, however he may have overlooked this problem. Since the tefilin were clearly made with this hair and it merely wore with time, is the shel rosh still kosher?
It is difficult to answer without seeing the Tefilin, if your rabbi saw them and has ruled them Kosher you should follow his ruling. However, it sounds like it is time to purchase your self a new pair of Tefilin. You should get a good "Gassot" pair that will last you your life time and will not have any Kashrut questions. It may be terribly disappointing finding out after many years that your Tefilin you wore were not Kosher.