I'll back Wayne on this.
Larry, from your description, the inability to push the piston back in tells me that at some point, through oil loss, the working piston/shaft is now contacting the divider piston, and that WILL be VERY difficult to push in. The gas pressure is on the order of 300+ psi, and even as the divider piston moves up (toward the working piston) with oil loss, the pressure remains fairly high, but the shock will NOT be functioning correctly if there has been enough oil loss, which your description tells me has happened. If the shaft is hard to push in from the very top of its stroke, I'm of the opinion that there is NO oil left in the tube.
As far as the ssssllllloooooowwwww action of the (presume new???) Bilstein on the bench, the seals in these shocks are very tight when hew. After the shocks have been run you will find them more "normal" in operation.
But as Wayne sez, on the car is what counts. The only other way to demonstrate this is to be able to put the shocks on a shock dyno and read the actual damping forces generated by putting the shock through a stroke cycle and measuring/recording the values. But shock dynos are kind of hard to find in the performance market---mostly shock manufacturers and big race teams, services which are typically unavailable to the public at large.