I went through this same experience with a throwout bearing that only had a few hundred miles on it. Short of submerging the used bearing in melted grease, I couldn't see a way to lube it. Replaced it with a USA made bearing from NAPA and all is good a few thousand miles later. A couple of things that helped me do this by myself with the same SM420 trans but not 4 wheel drive. You can make guide rods by cutting the heads off long bolts and letting the trans slide back on these. I found I could only use 2 of the 4 trans holes for this. This made it easier but it was not just simply slide back and forth. I struggled with positioning the throwout bearing, the fork, and the trans. Decided I could slip the fork in later. Big mistake and I had to pull the trans again.
