Hello, I have 2 fluorescent light fixtures in my garage, both controlled by the same switch. Each fixture has 2 x 8ft bulbs in them. One full fixture works fine when I turn the switch on. Up until this morning the second fixture would only come on if I rotated or jiggled the bulbs. Then after rotating and jiggling they went out completely and won't come back on. I replaced both bulbs and its still no good. I have a feeling it may be the sockets or ballast but I'm not sure how to test it. I did buy a spare ballast but it needs to be wired differently than the magnetic type I removed. So I'm wondering the best way to test the socket(s) first. There are 4 sockets, 2 on each side of the bulb. One socket has white leads only, the other has black leads only. Obviously this was the side taking voltage from the source. My source voltage is fine. I have a multimeter but not sure how to use it ;)

Thanks in advance.

First, don't assume the white wires are "neutrals." The output of a fluorescent ballast is not grounded. It also operates at around 500 volts, so turn off the circuit breaker before working on a ballast.

Usually you can see a bad "tombstone." The socket will be cracked, the tube will fit loosely, the socket will fit loosely in the fixture, wires will be loose, etc.

Chances are you have a weak ballast. Replace it and see if it solves your problem. Make sure the new ballast is rated for the lamp you are using.

Also, if your old ballast does not specifically say "NO PCB's," then wear rubber gloves and dispose of it as hazardous waste.