I have a pretty good relationship with Dale. He's a builder with a pretty good sized crew and busier than a one-armed paper hanger. Seeing as it was dead before I borrowed it, he'll pay for the rebuild, I'll throw in my time to diagnose, remove and replace.
Neither he nor his crew is known for taking care of the equipment so I fix his tools, do a little repair welding for him and generally keep things going. In return, I get to use whatever I need as long as it isn't needed on the job. Works out great for both of us and he knows I'll return anything I borrow in as good as, or often better than the condition I borrowed it in.