>>Somewhere I read that the original pump is rebuildable.
I'm going to take it apart and see what I can see.
Has anyone else done this?
>>

Your problem is brushes.
The Kit comes with two O rings , a seal, and a pair of brushes.
Nothing hard at all.
These pumps are just a vane impeller pump and not much in there to go wrong.. most are just worn brushes or the check valve gets gummed up.
Pay Paul Parts has the kit
I think the last one I did was $14.