I'm wondering if the filter was too small for the pump. Horsepower is deceptive in pools--unlike cars, more isn't usually better. Today's 3/4 hp pumps are quieter and more efficient, but your filter needs to be big enough.

Generally, a slightly over-sized filter will not stress your pump and will do the job better. With all 3 types of filter, Sand, DE, and Cartridge, too big a pump WILL damage the filter sooner or later, and back-pressure from too-small a filter could damage the pump over time.

I also wonder if the pump was mis-mounted so vibration could have gotten to it.

I also tend to suspect that most combo pump/filter units are over-powered for the filter and should have either bigger filters or smaller pumps. I cannot prove it, but the combos always seem to have excessively sized pumps.