Well, I'm kind of proud of myself. No, I didn't fix the sink myself, but I did diagnose the problem correctly. The nuts were the wrong size - fractionally too large.

A neighbor fixed it who had been out of town for 3 weeks. He mostly is an over-the-road truck driver, but had a small business doing home renovations and repairs before the economy and construction went south. It looks to him like the plumbing company that installed the sink used the nuts from the old sink. They did use plumber's putty, but also then used silicone just under and around the lip on the inside of the basins to compensate. He bought the correct sized nuts and a container of plumbers putty for $12.80 at Lowes and fixed it. He didn't want me to pay him except the $12.80 but I want to feel free to call on him again. He would not quote a price for his labor, but finally said, "It took me less than an hour. If you must pay me, pay me what you think is fair and that you can afford." I paid him for the parts plus $50.00. Do you think that was fair? Should I have paid him more or less?