lol, theres not much to replace in a blower. 4 bearings, 4 seals, some gaskets and aerobic sealer. AS long as the blower does not appear to be self destructing inside the clearances are probably close if someone had it apart. They are pretty simple. so is this a old detroit blower with weiand endplates? Can you upload a pic?
If the engine started smoking blue and the the enginge has no problems, its the seals. Seals can also be damaged when some one slides them on in a rebuild. If you bought it on ebay, i see plenty of people take a stock wore out blower apart, put it right back together and say its rebuilt. A wore out blower is still a good start .I guess if its leaking out the front cover, it would be hard for you to monitor the oil level in the blower. Is this a street car?