First, rotate known good lamps from one of the good sections to make sure you don't have any bum lamps. Next, you'll have to open the socket troughs to look for secondary shorts or faults to ground. Then, change that ballast which could be bad from the factory...trust me, not far fetched. Also, don't be surprised if the person who wired the previously ballast wired it wrongly. Most of the time, a six-lamp combination ballast is used for a five-lamp configuration and some of the lamp leads are capped off per the wiring diagram on the label. I'd double check the secondary wiring.
Hope this helps,
Andy
BTW, the model #1232 probably means its a 4-5-6 lamp combination ballast for 12' to 32'. So, (5) 6' lamps (F72T12 H.O.'s) equals 30' total lamp footage, which should be the correct ballast. If the lamps are vertical, check the bottom socket troughs first since rain water will travel south down the lamps to the bottom sockets to cause ground faults, shorts and general havoc.
[This message has been edited by cavo148 (edited 05-28-2005).]
