Center spray arm not spinning

How does water get into the center spray arm to make it rotate.
Mine does not seem to be moving.
Do both arms rotate at the same time ??
There is plenty of water because the bottom arm rotates very well.
Thanks, Larry

Here are your parts
Parts for Frigidaire FDB949GFB2 Dishwasher - AppliancePartsPros.com

[COLOR=“Blue”]Do both arms rotate at the same time ??[/COLOR]
See the manual.

Below is a link to a manual.
You will have to join the site and be logged in to be able to download it.
http://appliancejunk.com/forums/index.php?action=downloads;sa=view;down=248

Check that the holes on the end of the spray arm are clean.

Check/clean the pump and it’s filters.