On Jul 28, 10:26*pm, rank beginner wrote:

http://i209.photobucket.com/albums/b...alltile_01.jpg

http://i209.photobucket.com/albums/b...alltile_02.jpg

Should I regrout the whole cracked area?

Probably.

If so, should all the old
grout be scraped out first?

Or the greatest portion of it.

What would be the best way to do that (if
indeed that is what I should do)? Tools?

The Dremel. The grout removal tool/bit works great.

Also, is it a problem if water has seeped into the crack a bit?

Probably not.

You could just patch it with caulk, with or without "real" prep.

The underlying issue is what caused it to crack, probably related to
the substrate material/installation but maybe also what goes on in the
room overhead (if any).

If they're practicing martial arts up there, etc., enough flex may
have been induced to cause the crack.
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- gpsman