BOSTON–Tenants in the apartment building at 437 Market St. reported Monday that they experience a gnawing feeling of guilt every time they ask Hank Hudson, the 82-year-old maintenance man, to repair anything. "The other day, my sink was clogged and, at first, I was going to ask Hank to fix it," Apt. 4B tenant Julie Winters said Monday. "Then I remembered the time he repaired the furnace and coughed for weeks afterwards. In the end, I just bought a snake and did it myself."