speedo problems

I was out on a ride yesterday and looked down at the speedo (something I don’t do that much) and it was bouncing up and down. I was looking at it the rest of the day. By the time I got home it was reading about ½ the speed I was going. I pulled the part out by the trans and looked at it. (Not sure what I am looking for) but I cleaned it off and put it back in. I am thinking that the cable is gone. But I am asking around to see what everyone thinks. It’s a 94 cbr 1000f (if anyone has a service book lying around I would love to look at it a few days till mine comes in.)

First of all a question... is the speedo cable attached to the tranny?? I never seen one like that, every one that I've seen have it in the front hub..but of course I haven't been around bikes too long.

My VF500 did the same thing right before the cable snapped. Remove the cable and see if it spins freely and whether or not one end actually spins the other. If all is not well, order a new cable.