The following tables indicate different parts number between models HR-S5900U and HR-S3900EN. PACKING AND ACCESSORY ASSEMBLY<M1> PACKING AND ACCESSORY ASSEMBLY<M1> is indicated on the parts list. FINAL ASSEMBLY<M2> FINAL ASSEMBLY<M2> is indicated on the parts list. MECHANISM ASSEMBLY<M4> MECHANISM ASSEMBLY<M4> is indicated on the parts list. MAIN BOARD ASSEMBLY<03>