Grove RT questions

Hello. I bought an old (68649 sn) 518 and a 528c (798XX sn) from a local quarry for around scrap value. The 518 runs and functions fine with the exception of the front steer, greer lmi, weak brakes, and a small stabilizer cylinder leak. The steering problem is that it seems to turn fine to the left but kind of bumps and returns when turning to the right. I'm assuming the greer lohd-900 series is an lmi or load cell. it gets power, reads +1, but doesn't change when I put a load on it. I can't find any manuals or information on it over the internet. We can move it around the yard with rear steer enough to do what we want to do with it but would like to have the added safety of an actual reading of the weight without guessing. . The 528 needs a water pump and gasket on the inspection plate on the side of the block (both 5.9 Cummins), but the swing brake, not the transport lock, won't release. The knob on the dash feels like it isn't engaging anything when actuated. Is this air or hydraulicly activated, or both? There is a PAT DS 350 GW that we are starting to figure out that seems to be working. Since these are both the same basic series cranes, could I buy a shop manual for the heavier/newer crane and be fairly sure that most of the systems were the same? If so, where could I source it? Thanks in advance.