Whewwwwwww! That was close! Glad you and yours made it home in one piece.
Brought my Whirlpool portable dryer home in the back of a mini-van with it resting on it's side. And yes, one to many hard stops and that dryer would have lurched into the back seat and maybe even come towards the driver, Moi! As it was had to go easy on some turns as the unit slide about, which after awhile made using the rear view mirror pretty much useless, so had to switch to the driver's side mirror. Still only had about an 45 minute drive, nothing like your 8 hour BOS to DC run. Yes, the things we do for love.
If you go to the Sears parts website, you can see diagrams of not only the parts in questions, but the entire machine in general. This should give you an idea of where the pump is, so you can perhaps take off a panel and see what is going on when you engage the unit. You'll probably want to have lots of towels handy and by all means don't keep that washer plugged in long. Water and electric power do not mix! You may be able to shine a light on the pump and see if something is "stuck".
It might just be a sock or something worked it's way down and is jamming something up. It would explain why the woman only used the machine once then put it away.
Oh yes, scan eBay as there are tons of Whirlpool pumps up at the moment, and one might be the part you need.
L.
