I start by carefully opening the sprue plate as I have often found production debris under plate that will scratch the upper surface of the mold blocks. I only open it and do not close it until my prep is finished.
Next, I use 000 steel wool and lightly polish the upper surface of the box. The idea isn't to remove metal, just polish it. You generally will see wear under the point where the sprue plate pivots. I often find material trapped under here. The area needs to be polish up well as if not this area will cause problems later with the sprue plate fitting flush to the blocks. I then stone the underside of the sprue plate with a 600 grit stone lubed with WD-40. You can see the wear on that stone, it has seen a lot of sprue plates in it's life!
With that done I completely clean the mold, usually with a spray bath of WD-40. Be sure to flush the sprue plate screw hole with fluid. Steel wool will get trapped in there and corrode the screw threads down with heat and use.I then dry with a soft towel and start to put it back together. You can see the new block design in this photo. I really like the beveled edges and the mold designation. I would like to think I had something to do with that!
You will also see that I use a small amount of anti-seize on the sprue plate screw threads and down inside the screw hole.
That's it, this mold is almost ready for use. That will be the subject of another post.
