Gary, back last summer when I was working on getting my 107 going, I discovered the same thing the hard way! Old S/G was bad, wouldn't spin fast enough or with enough power. After cleaning it it couldn't make up it's mind which way to rotate, it was shaking back and forth.
Rather strange, but that's okay, I had a spare off a Briggs 10hp laying around. Little did I know, it was mounted the opposite direction on that engine, so once on my 107 everything spun backwards!
With a little experimenting, I found that I was able to correct the issue by swapping the good armature from the S/G that spun the wrong way into the casing of the original S/G that was no good. The result was a fast, strong S/G with possibly more power than needed, as the Briggs didn't have a compression release.