Our 3000 did that, too. In our case, the seal wore a groove into the shaft.
The rest of the pump was in ok shape so I took the shaft to a pro machine rebuilder (they rebuild large industrial machinery). I thought they'd do the standard things - weld the groove & turn the weld back down.
When I got it back, I found they'd cut a wider groove, then built it up with a flame sprayed-on ceramic (hard stuff!), then turned that flush with the shaft diameter.
I asked 'em why they did it this way and they said it's been their experience that welding a small diameter shaft sometimes causes the shaft to bend slightly, and rebuilding and remachining a bowed shaft then becomes a game of tail-chasing. From the welding I've done, I instantly knew what they meant. They said the ceramic is so hard, I'd be dead before the seal wore a groove in that spot again. Cost was $150, info I gained was worth a lot more than that.