Ron, I'll gladly leave pump size and flow issues to experts like Mark and Al (if I know a little about what they're talking about, it's only from reading their threads )

However, it's easy, usually, to see if the shaft seal has failed, all you need do is look for a drip at the motor/ housing interface when the pump is running (a puddle coming from under said interface is a good indication as well)

Good luck with keeping the motor running another 15 years.