The reason most of our coaches have so few miles is because we will not drive them when there are air leaks. So for the most part they sit in our garages while we spend days chasing down leaks. Or we lie and say our buses are leak free and we just drive them.

What you did not state was the nature of the leak. How fast does air leak down, is it from the brakes systems, the suspension (the leans), or from the aux system. Once you have narrowed it down then isolating the leak is a matter of further isolating the sub system that is leaking. I can make leak detection sound simple, but all the old timers here will tell you that air leaks are frustrating and at times very difficult to locate. Other times they are easy to find and fix.

For now I would make fixing the leaks a condition of the sale. You will get enough practice later on finding them yourself. No sense starting out chasing problems.