how to remove lower wash arm

Dishwasher Repair
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1

I have a cracked lower spray arm on my GE and would like to know how to remove it,heres what I tried holding the arm then trying to remove the hub above it counter clockwise that wouldn’t work then i removed the phillips screw that holds a little gear on it and that dosen’t work can you help,and also i would need the part number so i can order it on your sight.Thank you