New pump and motor=tripping breaker

Hope some of the experts out there have some thoughts.

Just replaced the motor on my Challenger pump and completely replaced the booster pump for the pool cleaner.

Got all of this put together last night and everything was running good except that the shaft seal that I put on the new motor was leaking--don't know if I did not put it in right or ended up with a defective one--guessing latter!

No matter, went up this AM and got new shaft seal and put the thing back together again. Fired up main pump and voila, no leaks. But when I turned on the booster, the breaker tripped. Checked all my wiring and could not find anything amiss.

The new pump motor is AO Smith UQC1152, 1.5hp uprated that draws 8 amps. The booster is Pentair LA01N that draws 6.5 amps. This is on a 20A circuit. The motor is actually a downsize from the full rated 1.5HP motor that just went bad, so I am actually drawing fewer amps than before. And like I said, it worked last night just fine.

I guess next step is to replace breaker, but that seems awfully coincidental that in 12 hours the breaker went bad. Plus if the breaker was bad, it would seem that it would trip under any load or be problematic to reset--at least that is what my limited electrical experience has led me to believe.

So while I will grab a breaker when out next, as having the booster running is not important until the pool water filters clear from being down for a week, I was hoping that someone might have some other ideas or similar situation they have run into.

Thanks.

Paul