[V8] Radio for 1990 V8?

[Brad Hartman]

My original 1990 V8 factory radio still works, but the maximum volume has 
significantly dropped over the past year or so and it's just not loud enough 
now (why I have no clue).

Does anyone:

1) Know if there's a simple fix for this?

or

2) Have a used replacement radio for sale? (it's the Audi/Bose radio)

Thanks,

Brad