Trying to get repairs done to large machines can be very difficult, especially if you don't know exactly what the problem is. There are various ways that you can figure out what the problem is, but some of them can be much more practical and efficient than others.
Disassembling the Machine
One way that you can figure out what's going on with the machine that you working on is to take it apart until you get to the problem with it. Once you get to where the problem is, you can fix it and then start putting the machine back together again. The plus side to that is that you are going to get the problem fixed. The down side is that you have spent a lot of time taking apart machine to get to the problem, and while that amount of time can be negligible if the problem is relatively shallow, the deeper the problem is, the more wasted time you are going to have to spend taking everything apart, even if it isn't near the problem. Luckily, there are other ways that you can find out what the problem is.
A fiberscope is a tool that you can use to visualize what is deep down inside the machine. It's a cable with a camera on one end and a view piece on the other. You can control it at your end, which will let you direct the scope to various parts of your machine. The cable of the scope is made up of fiber optic strands. Fiber optics are made up of a special kind of glass. Those strands are what transmit the image back to you. There are also some plusses and minuses to using a fiberscope to figure out what the problem is. One plus is that you are able to get into tight spaces without having to take apart the machine to otherwise access them. One problem with the fiberscope is that it can't bend at an acute angle. That's because you run the risk of breaking the fiber optic strands, which would negate the efficacy of the scope to use in aiding your repairs.
If you are trying to figure out what is going on with a large machine, there are different ways to do it. You want to make sure that you are doing it in the most efficient manner, so that you aren't wasting your time.