Here's the platen all set up, with giant balloon letters, before and after inking up. I ran it once very slowly and carefully without ink to make sure I wasn't going to squash anything in the process of adjusting the platen.
We adjusted the platen's height with the four screws on the back. We started with the platen closed, so we could get it approximately the right height, and then tinkered with them one by one by trial and error. I was very conservative with the pressure, focusing on getting the print even. I'll probably have to raise it a bit more in the future. Wowza, look at it go (don't worry, we oiled it right after I shot this.):