I have been using and repairing these tanks for many years and can tell you it is a great machine. The only thing you would want to do is change the seals. Buy seal material from MicroTek, it's self stick and an assorted pack is about $25, 3 8x10 sheets of 3 thicknesses. You'll have enough material to do everything you own and even do friends cameras too. Just clean out the old gook, cut the strips, peel and stick. That's it. There are internal seals in the body but you'd have to open it to get to them. If the body doesn't leak light, leave it alone.
Be sure to cock the camera before taking off the lens and also be sure the body and lens are cocked before mounting the lens. You can do serious damage by not doing this correctly.
Also DON'T FORCE ANYTHING!
Don't touch the mirror it is very fragile and looks like it's bent. It sits higher on one corner than the other. A common mistake is to try and straighten it. I replace mirros on many RBs because of this.
If you need any technical info, e-mail me at AUTOMAX1@JUNO.COM.