For your MaxxAir model 8900K, we have the Replacement Operator Mechanism for MaxxAir MaxxFan Plus or MaxxFan Deluxe Roof Vents # MA10-20281K-1AF and the Replacement Lift Arm for MaxxFan Roof Vents # MA10-20222KS. From your pictures and what you mention being broken. These are the parts that you will need to fix your 8900K fan. view full answer...