Hi, a few years ago, I dropped my Tefillin on a chair, and a slight bit of the paint chipped off. I then, as I was a young boy and did not know the halachot, simply colored in the small part with sharpie. I recently just remembered that I did this. Are my Tefillin kosher? If not, what steps should I take from here?
Yes, your tefillin are kosher. The ink from a standard marker is probably kosher for tefillin. In addition while the straps being black is crucial for the kashrus of tefillin, for the “batim” [tefillin boxes] the black is less integral.
The entire painting of the batim black involves a dispute among rishonim (the principle halachah le-Moshe mi-Sinai refers to the straps), some maintaining that this has the same status as the straps, and others writing that it is only a matter of Zeh Keili ve-Anveihu.
The Be’er Heitev cites from the Bach that the black of the tefillin themselves is not crucial, and this appears to be the principle opinion, though the Be’er Heitev writes that one should not be lenient in this matter.