Hey, McCracken, wherebouts in OR are ya? The show I go to about every other year is a model car show, the SABA puts it on. It's not an RC show, but I build 1/25 trucks and cars, and this crane...
I have taken about a couple years off on doing anything with this project other than operate it, but I got busy lately. I tried a 10 lb lift to see what would happen. It revealed some weak points, but did the lift without any damage.
One weak point was the slewing pivot, rather a hub and spindle affair. The spindle was fine, a 1/2 stainless steel bar. There was enough play in the hub part, basically brass tube inserted through the 1 1/4" thick base plate to allow fore and aft rock, thus some interference. It took 10 lbs to reveal that.
So a new hub was turned from thick brass bar and a larger hole drilled to accept it. It is stepped so it looks like it's sitting on top, but it goes all the way down through, and held in with a set screw.
I rebuilt this block too. It needed a stronger hook, so I made a copper one. I'll probably replace it later on with a double hook, but for now this holds with all authority. The thin plates between the sheaves were warped, so I made thicker ones, now the block behaves far more smoothly. That overhaul took most of the day!
Another 10 lb "pick" was done to check out the improvements, and it all works quite nicely.