Follow this link and download the manual,
RCBS Parts Book
It will at least show you some detail of how everything goes together, as well as give you the part numbers you need to get any replacement parts for your press. If it is the manual index look on page 8, and the progressive one look on page 9.
Give RCBS a call and tell them what you need. Bear in mind this press has been discontinued, so some parts might not be available. I would try and get the index rod, and a couple of the nylon index bushings, and actually the whole index assembly if you can.
I have had mine since the early 80's and no telling how many rounds it has kicked out. They are a solid press even if you wear out a few parts, it takes a ton of rounds to do so and several years to boot.
As for the index plate, the trick I use is to screw the middle screw in only tight enough that the plate stops when it rotates to the next hole. Trying to get it too tight will only give you fits. Loose isn't a big deal once you have things running, just be sure to snug the set screw or it will tighten down as you go on it's own.