Same problem with mine. I mike'd the shafts and the u-loint bores as well as the bearing bores and there was an interference fit of ~.001 if I recall correctly. I had to use a small fine abrasive flapper wheel to open up the bearing to get the shaft to fit. On the u-joint press fit I had to carefully remove some metal from the shaft ends a little at a time. I took just enough to make a tight slip fit using a micrometer to measure the amount of material removed and a Magic Marker to indicate the tight spots that needed to be worked. Go slow and don't get aggressive with material removal -- it's a lot easier to remove material than to put it back if you go too far.

Also a tip: the u-joints have set screws to hold them on the shafts. You really don't want these to come apart on their own. Once everything was assembled and adjusted to my liking I marked where the set screws engage on the shaft. I then disassembled everything and set up the shafts in my mill and using an end mill plunged a locating bore slightly larger in diameter than the set screw and ~half the diameter deep. I made only one of these per shaft end so that to pull apart the assemble would require shearing one of the set screws. You can use a drill where I used a mill -- even a hand drilled locating hole is better than relying on the clamping force of a small set screw alone.