TAOHS-JP3 to TAOHS-KP1

Can someone please help with circuit or notes for retro-fitting a TAOHS-JP3 with a TAOHS-KP1.
The TAOHS-JP3 is from a Yamaha CDX-810 CD Player and has an extra circuit board on the side, looks like the KP1 replacement has SMD components and this extra board in not needed.