Speedometer will only go up to 40mph, and idea how to fix?

Well, I took out the dash and I added the white face thingys, and everything seemed fine. When I put everything back together the speedo would only go up to 35mph. So I took it apart again to see if anything was sticking, and everything seemed fine, everything seemed to move without sticking. I hooked it up again, and now the speedo work up for 40mph, which is better, but still not right. Does anyone know what might be going on?? It's one of those things where I'm starting to think I should have left is as was.:banghead:

Any help on this matter?

and why is that speedo cable so short?? How annoying! That the only thing I can think of is that it isn't in far enough... It is clipped in place though.

Thanks!