It may be naive but I do not think it silly. I have usually tried to get a service manual and schematic for my equipment, especially if I plan to keep it for a long time or if I have thoughts of modifications.
A few years back, I had an input noise problem with a Pioneer Elite tuner and I asked a local dealer/tech if he would look at it for me. He said that it would be pointless without a schematic because of the complexity of that unit but, when I said that I had the service manual and schematic, he readily took it on. Cost me 1 hour of his time and about $10 in parts. That was 12 years ago and the tuner continues to work superbly.
Kal