The next day we met and I had the opportunity to inspect the situation. Hard water had caused a calcium build up in his shower valve. I recommended an experienced plumber who could come and address the issue with a full complement of tools necessary to replace the rough in. In my estimation, the calcium build up was beyond a second attempt at repair and the situation needed the extensive specialty work and warranty a licensed plumber could provide. That second opinion cost him nothing but did help his decision making.
The pool drains were a different matter entirely. The original installation did not use stainless steel screws to secure the drain covers. In the intervening years these screws rusted away in place, and the Polaris skimmer eventually was able to knock loose the covers, causing a safety hazard to swimmers. Knowing that he would not have an easy time finding a pool service company that can fix this problem (especially in 54 degree water), I offered to do the dive myself. I'm a certified recreational diver so rounding up the tools was not difficult. The solution called for removing/grinding down the rusted screws, re-drilling some holes and replacing the screws with stainless steel versions...in 6 ft of bone-chilling water. How would you have done it?
The point of this story is that I was able to complete the job safely and to the satisfaction of the customer. He did not have to drain the pool nor wait until spring to fix the problem. Good planning, some obsolete hand tools and a tolerance for cold water dives made all the difference.