The bearings should be somewhere between a slightly loose fit to a gentle press/tap, as mentioned above, they are held in place by the all the various tapers and the preload. Only headset i've had where they aren't removable by "hand" are Chris King which needs a proper bearing press.
(By hand i mean sometimes they need a tap with something, no violence tho!)
Great, thanks for the further clarification! I have only had integrated headsets on 2 bikes so far; all the other frames I have had have been traditional types where you press in top and bottom cups.
So yeah, I seem to remember the CAAD9 bearing dropping easily into the head tube.
I know cannondale say no spacer above the stem, but could you just try taking your 10mm from under the stem and putting it on top. And see what happens. Just to suck it and see......
I went from a Deda Zero100 stem to a Deda Superleggero.
The Zero100 had 2 x 5mm spacers under it, with none on the top.
The Superleggero has a slightly lower stack height, so I put a 3mm spacer on the top. I have also tried a 5mm spacer, in case the steerer was still sticking out the top of the 3mm spacer.
With both configs I am still getting the problem.