Hi!

Bose service is probably not an option here.

I doubt that the change will be easily implemented. However, I would
definitely try Bose customer service in your list of possible ideas. They
might offer a straight up trade for the unit or maybe even offer a pro-rated
exchange.

While I can't offer any advice on taking the unit apart, if and when you do,
carefully examining the circuit board may reveal some method of changing the
frequency steps for the AM band. In the best case, there might be a soldered
shunt or jumper bridge over a set of terminals to direct the microcontroller
as to what set of tuning instructions it should follow.

William