I am using the lightning pump. So far so good - can be had for less $80 to $90 (Johnson is $175)
After looking at the factory pump - which really appears to be a hefty design, I am beginning to feel the hose on the factory pump may be involved with the failure.
Only our pump (MB too of course) has a hose connected. I think this hose may be doing the opposite of its intended purpose. Instead of draining I think it may be an inlet for water - any car that sat for any length of time, especially during cold weather, would be damaged by water in the magnetic drive.
I am only guessing but when I took apart my failed factory pump the magent was cracked in half and the inside appeared "rusty"
The lightning pump does not have the connector for the hose - so just plug the hose when the pump is swapped.

These guys delivered quick: http://www.buyfordracing.com/shop/pr...id=580cPath=10