Good question since no seller takes the old one as a core.

Disintegrating bearings leads to catastrophic failure but the seal behind the front cover gets deformed and leads to an annoying front end leak. Should be a simple matter to straighten the tabs and have a look inside the pump to determine why it's not rebuildable.

It would be great if someone could retrofit 617 pump guts into a 603 case. You never hear of 617 pump drives disintegrating. I've done a simple rebuild of a 617 pump on the engine to get the brakes working so I could get the car for free!

Sixto
87 300D