Do it yourself

Just a quick update on my regrouting project in the master bath, which has major tile (up the walls and tub surround including overhead in tub area). A while back, Reed suggested getting a little hand grout saw, which I used for about 2 minutes before deciding that I needed MORE POWER. So, off I went to HD to get a dremmel. Now, I'm really cooking on the project. Of course, now that I'm digging the old grout out, half of the tiles are falling off the walls. Lesson learned: put towels on the floor! Fortunately, only one broken tile so far. Starting to tackle the tub area and am finding no major water damage behind the tile (yet), but it is damp. Didn't see any backer board back there, just wood (bath was built in the 50s). Also there is a gap between the wood and the tub behind the tile, which I may fill with caulk or something prior to replacing the tile. Oh, BTW, there is a recessed overhead light in the tub enclosure. While changing the light bulb, I noticed that the rubber gasket is brittle and the about two inches of insulation around the wiring from the socket is decayed and flaking. I've not used the light because it seems unsafe. Ideas? Should I fix, replace, ? -- Mary M. Oak Ridge, TN