FYI: You don't need to remove the odometer knob to remove the "guts" from the instrument cluster. All you need to do is pull it out to the extent of it's spring. There's a cutout in the speedo faceplate for it to pass through.
If it you pulled it all of the way out and now it won't stay back in then one of two things occurred:
a) You popped off the E-cilp, washer and spring that hold it on.
b) You broke off the tabs that hold it into the instr. cluster housing.
The good news is that if you messed it up they are relatively cheap to replace: 62111459244 - about $9-10.