Yes, we know, we've covered the basics of this. The makeup was terrible. The suit was heavy. The part was re-cast. He was either getting sprayed with oil or melted chocolate depending on what day it was. But even that wasn't the sum total of the misery that our poor Tin Man had whilst making this movie.
The costume department decided that the best way to make the Tin Man look stiff was for his costume to actually be stiff. This was a department that didn't seem to prioritize the comfort of their performers. The outfit was in fact so stiff that Haley couldn't bend or sit down, so over the course of the entire twelve-hour day that he was wearing it, the only way he could take any weight off his feet was to lean against something for a while.