Most of them can be replaced, The problem is that every manufacturer uses a differant method to hold the pins in.
I replaced two different types last week, One used a drive pin, and the other punched around the part you push on and I have seen others that had a little clip ring similar to the clip that hold the bearing caps of the u-joint.
The next problem is to find a new pin.
I turned the ones I replaced on my lathe.
You should be able to find some one around you that has a lathe and can figure out what you need in the way of a pin.