I recently got a good deal on a mid 90's Carrera in Columbus EL. It arrived yesterday typically kind of dirty, but otherwise really nice shape. I was unable, however, to get the front wheel on and it turns out the left fork end was too narrow. I couldn't even get it onto the fork mount on my work stand and basically clamped it to the skewer axle.

The left side measured 7.5 mm vs 10 mm on the good side. No signs of any damage, there or anywhere else. I fixed it this morning, after experimenting with a few methods, by putting a vise grip on the forward end, then using a large set of plumbers pliers to get some steady, nervous, torque on it. Luckily, no snaps, and I'm able to get the wheel on and off and everything is aligned well.

I'm baffled as to how this would happen without signs of trauma. Any ideas and now that I cowboyed my way through this, is there an accepted standard for fixing this?

And OK, I know pics are required, so here she is torn down for cleaning. Came with a nice Record 8 speed group.