Sometimes the Web surprises you. After an hour or two of fruitless searching yesterday, I posted this thread asking for info on the BK 3025. Today, I decided to try one more time but search for BK 3025 "function generator" instead of "sweep generator". One of the results near the top of the list was:
It looked like nothing, but then I noticed the "download" tab. Lo and behold, the service information for the unit with a schematic.
This might be a good site to keep track of since they supply this kind of info for free.