I haven't sold Goulds for years, but they are a good pump last time I knew. I don't know about wrapping extra screen around the factory one. That may not have been a good idea.
Pump companies have over the years tried to get a little edge on their competitors by cheapening something on the pump/motor to save a penny or two. (You know bean counters). This happened to Red Jacket a few years back. They had all kinds of shaft problems.
If the pump is within the years warranty, I would call Goulds directly. They don't like bad publicity and will probably see to it he gets a new unit no matter what went wrong or why.
You should probably know Goulds, Red Jacket and a host of other pump companies are owned by ITT corp and they are Hugh. But the bad publicity thing is not something they want to deal with.
You should check his tank. Water logging is a good reason for a shaft to get stressed out from all the starts and stops.