Thanks Laitch,
I was able to remove the impeller and get it free up by tapping the shaft back a tad.
I used this method
http://hrsbstaff.ednet.ns.ca/bvogel/K100/oil_pump/oil-pump-seals-replacement.htmAnd everything looked the same with exception to the impeller and lack of spacer.
It appears that the cast impeller (listed as a "rotor") could work if I ground down where the spacer would go, seems to be about 1/16" too deep therefore putting too much pressure on the spring seal.
Here is a picture of mine installed, with slip-ring seal 11411741870, and shaft seal 11411460329
Would leaving these in place finding a new stamped steel impeller with the spacer would work?
All threads I saw already had the newer stamper impeller so didn't address using the cast one of not.
Most diagrams have the cast "rotor" with a spacer, as mentioned I don't know how this one was prior to previous owner trying to fix. I looked at what came up when I google BMW fiche, and the diagrams I found show the cast, but I must be looking at something different.
With this said, do you think a new impeller with spacer resolve this?
I haven't been able to find them online so far but will keep searching.
Thanks!