I recently replaced the broken vanes in my 1hp g625 compressor with a replacement set that I ordered. After carefully putting everything back together I turned it on and noticed that it made a loud humming sound and gave a slight vibration but other than that did nothing at all. I took everything apart and noticed that the rotar seemed to be jammed. When I turned it off I could rotate it with my hand rather easily but when I turned it on it would jam. Several times I repeated this and only once did it get up to full speed (but the next time, after changing nothing, it jammed) every other time the same result as before. When it was off I could rotate it easily but eventually noticed that every half-turn or so there would be a brief and very faint scraping sound. Once or twice when I turned it on it would quickly spin about 3/4 to 1/2 turn only to abruptly jam again. I could find nothing wrong and nothing broken or out of place.
What is wrong and how do I fix it?
I need to get my system running as quickly and inexpensively as possible

thanks in advance
-Scott

Take great care of it, or let someone else have it.