I bought my first sometime between 82-88, they work great. The angle of the cut is fine too, keep the guide rod pushed up in the slot with the hand holding the clamp. It's a hell of lot more precise that hand honing on a bench stone.
Also, don't use the thumb screw to tighten the clamp, use it to preset the two sides of the clamp parallel to the blade and then tighten the clamp with a screwdriver. This is real important when using the tip of the clamp to hold a small blade.
I switched to diamond hones a long time ago and they work well too.
