3) What exactly happened?
Several years ago we had a system in a church and every so often there would be a cipher. Nobody could figure out what was going on. The builder was in there repeatedly, we even stopped in at the church on our way to the Boston AIO in 2001, all to no avail. It wasn't until we got a 'Yes' to a couple of the questions below that we figured out what was happening.
An organist calls you can tells you their organ isn't working, but trying to get them to define what they mean by 'it's not working' can be a headache. Then there are the times when you make a long drive to service an instrument, only to find it works just fine when you get there. It seams obvious, but finding out some basic information, particularly before you leave the shop, can be crucial. I will probably ask these same questions when you call me.
a. Exactly what happened?
b. When did it happen?
c. What order did the organist do things in?
d. What was on and what was off at the time?
e. Does it happen exactly the same way every time?
f. If you do something different, does the problem change?
g. Is there a common element?
When the organist first calls you they may not have the answer to any of these questions, they are not trained to think in these terms. The more information you have however, before you make a trip or call me, the better. Calling me to tell me that the organist told you that X isn't working doesn't give me a whole lot of information to work with in order guide you. If possible, may I suggest having the organist call you on a cell phone while they are sitting at the console. If the organist can't reproduce the problem, then there isn't much you can do to 'fix' it. If the organist does reproduce the problem while on the phone, you can then ask them some of the above questions.
Knowing that C2 on the Swell manual doesn't sound, but when the Swell stops are coupled to the Great they are just fine, gives you a lot of information. You know the stop tab is working, you know the pipe chamber is working, the problem is the console isn't recognizing that they key is pressed.
Being able to tell me that the Swell 2 and Great 2, and General 3 pistons don't work, but that the General 3 toe stud does work, is a lot of information. This tells you that dual magnetics are working and the computer understands what to do with General 3. In this case I would look for a common wire with the pistons that don't work.
The diagnostics on both the Legacy and Maestro Systems are fairly simple to use, you can probably talk the organist through the instructions over the phone, if not the organist, then somebody in the junior choir.
As for the church with the cipher, questions b. 'When did it happen?', and g. 'Is there a common element?', pointed us in the right direction, something nobody noticed at first. The problem only ever happened at night. Turns out that on the outside wall of the church there was a security light; at night, if it detected motion, the light would come on. The high power cable for this security light ran up the wall really close to the console to chamber data cable. When that security light turned on, it created interference in the data.
Next question "Where is the problem?"