Cracking grout in shower stall
I'm thinking that just re-applying silicone caulking over the cracked grout would not be enough of a long term solution. But I also don't want to re-grout the whole shower stall, as most of the grout everywhere else is still nice and white. Is it enough to remove the grout where I see cracking (plus some overlap), and to re-grout those areas? Not sure if there is any issue with the way that the new grout would "bond" (or not bond) to the old grout.
Also, under the shower jamb, I ripped out existing caulking to find out that there wasn't any grout there at all... was just a gap about 3-4mm. Is this normal? Should I also grout over this gap as well?