If there was any offset the seal was not doing its job. I think you found the problem.

When pulling the pump the seal will come with. It needs to be installed into the tank before putting in the new pump. Sometimes it will try to go into the tank with the pump and you have to start over.

I have on occasion reused the old seal when the new seal wants to follow the pump into the tank.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)