tek light issues (ballast?)

[Skimmer Juice]

ok I got a new light , now Im just gonna try and get this one fixed . I took the fixture apart how do I tell wich ballast controls what switch? The one that controls the 4 bub's is the dead one. The ballast closet to the switches is white and the one mounted on the front off the fixture is black , here are some pics with the numbers. Not sure if this helps. I just want to know what ballast to remove to find the right replacement. Thanks again for any help