Water comes out under the ARM. Won't rinse

Dishwasher Repair
1

It does not rinse anymore. The water is coming out under the arm.

Can I lift the ARM up and out or is there a screw in the middle of the tower? Can I unscrew the unit under the ARM to get at what ever gasket or seal I need to replace.
How about part numbers?

2

Here are the parts. Your exact model number did not come up.
Replacement parts for GSD530tww models | AppliancePartsPros.com

This should help. It shows a couple types.
http://www.applianceaid.com/ge-dish.html
Check out #16.

Problem may be the following is toast. It is in the throat of the pump beneath the spray arm. It lets water into the throat when draining and is supposed to close when washing.
AP2038495