Try dealing with the parts department, information located below.
As you said, they may have different departments for different things. It would appear you where correct.
Parts and Manuals
Replacement parts, service manuals, and instruction manuals may be ordered from your local authorized Icom America dealer or from Icom America's Parts Department.
Icom America Parts Department
12421 Willows Road NE
Kirkland, WA 98012
Phone: (800) 346-0495
Monday – Friday 7:00 AM to 11:00, 12:00 to 4:00 PM Pacific Time
Will Call Hours (By appointment only)
Monday – Friday 7:30 AM to 12:00, 1:00 to 4:30 PM Pacific Time
Hope this helps and you can get the board you need.
--Shane
WP2ASS / ex KD6VXI