My guess is there is some special trick.
Yep, there is one indeed, it always is ...
At HFT you will find this kit (can't remember its name now, but if you are interested I can look it up at home). I used one adapter, can't remember what size. To push them in I used a 5/8" threaded rod (or was it 1/2", or maybe 3/8" ? - anyway chose the biggest size that can fit through the hole) with nuts and washers from Lowes and a solution of 50/50 water/dish soap. The trick is
that when pushing the new ones in you have to guide them or they will not go in straight, they will cock and jam (at one end the bushings have an appropriate hole in the center, that's the end where you will push them from, but at the other end -the leading end- the hole in the bushing is much larger so it has no guidance
). Therefore, as you push it in w/o guidance, it will cock and will not go in any more. That's your problem, I had it too. Apply the trick and you'll be fine, the pictures prove it.
The "trick": Have a closer look at the picture where you see a grey adapter, picture # 2 (is nothing else but a tube that fills the hole and keeps the rod centered with the bushing. Once I did that, the tube kept the bushing guided
and because of the water+soap (last picture) it went in like a charm. Build your own adapter from whatever you can find (wood is fine too). If interested I can post pictures of what I used tonight.
To achieve the required height per FRM, I gave it a "touch' at the end with the manual press. When measured with the depth caliper, I was right on the money.
Other magicians may have other tricks, but that was mine and it worked out for me very well. I cleaned them up a bit and gave them a black paint before installing. Don't they look pretty?