Lets start you out with an easy shove.
LO 9-6115-641-12: This is the Lubrication document. It tells you what, where, how and when to lubricate this gen set AND ENGINE. Its short, read it 1-2 times and then you at least know where to look for that info.
TM 9-6115-641-10: This is the bible.The operators manual, for the GEN SET. When you have a need to know something about the ENGINE, there is another TM. This should be read several times. You don't need to read every word. Skim. but skim with an open mind. It tells you more info than you will ever know or remember. So it's not going to hurt to give it a deep look, every now and then. And once again, you will KNOW where to look for GEN Set questions questions and answers. It will tell you how to PROPERLY emplace, use, shut down and do PMCS, (Preventive Maintenance and Services). It will tell you what you want to look at before you start the set, during operation and after shut down.
TM 9-6115-641-24: This book tells you how to Fix, Test, Remove and Replace anything on the GENERATOR Set. Not the engine. I can not stress how important it is to read the passages on a job you want to do, BEFORE doing it. Too many folks try to "just do it". Then run into problems. I can not point fingers. I did it that way 50 years ago. At some point, I found out there is a lot of info in the book to help me out. Make it faster and not break things. This is another book to skim a time or two. That way you have a general idea whats in it, and how to USE the TM.
TM 9-6115-641-24P: The Parts manual. Gives you the parts call out for the GENERATOR set. Not the engine. I would highly suggest you look at the book one time, from front to rear. There are a few items you would expect to find in it, that will not be there, and a few parts you expect to find there will NOT be there. They are in the engine TM. Then pay close attention to the UOC, (Uaeable on Code) There are a few parts listed in the TM, that are for the 400 hertz generator set. They are not going to help you, on your 60 hertz set. The explanation of the UOC is in the forward part of the TM.
TM 9-2815-252-24:
TM 9-2815-252-24P:
These are for the Engine. Everything I wrote about the TM's above, applies here. Just its for the Engine. Skim them 1-2 times.
You do not have to remember everything. But it sure helps when you know that the info is in the books. You then know where to find it. Have patience. Take your time. Before I do any procedure for the first time, I read the TM at least twice. There is no passage longer than a page or two. The TM's will not tell you everything, nor every problem and solution. It would be 10,000 pages long. The TM expects that you bring a little something to the job other than lunch. It is written for just about anyone to understand it. Non Rocket Science info. If you do not understand something, ask. The only stupid question is the question not asked. There are some really smart guys in this forum who can help you.