You may have to step up to a more aggresive polish. I would try the mothers powerball as some peeps on here have used with great success. If that doesn't work, you may need more abrasive polish. You can find aluminum polish compounds at Home Crappo in the tool aisle. You may wanna buy a 2 wheels or so for your drill. If that polish doesn't work, the only thing left I would think would be to try to wetsand the blower with 2000 grit working your way up to 3000 then follow up with the above polishing methods.
The above is only applicable providing the blower isn't cleared which I don't believe it
should be.
If you ar eon the M forums you must know IllM3 even though he recently sold his sick M!