Lighting, Light Fixtures, Ceiling and Exhaust Fans - flourescent light fixture problem?

I have a 2 bulb (48 inch) flourescent light fixture that is driving me nuts. Over the past 6 months or so, both lights would flicker a lot and then finally come on bright and stay that way. If it wasn't used for a while, the flickering would last even longer. This week, when the light gets turned on there is no real flickering, but the problem is the bulb never fully lights up. I would guess maybe 10 or 20% of its normal light level. So I replaced the bulbs (yes, with the correct wattage). The light came right on...for three on and off switches. Then it went right back to the low level light with some flickering ever time. So I decided to change out the ballast (no starter on this fixture). I got the proper ballast, installed it correctly, and put back in those new bulbs. Again, the light came right on and everything was great....for three or four on and offs.

I am completely out of ideas what could be going on. Could it be a problem with the ends where the bulb end meets the fixtures? The light is about five years old, but the company does still make that model. If the ends could be the problem, are those "universal" and can be purchased at Lowes, HD, electrical supply store, etc...or do from the manufacturer?

Thanks so much in advance for your help.
--Ryan:wall:

Make sure you grounded the fixture. Older flours are finickey about this. And yes on some fixtures i have seen in the past having the post crossed screw it up also. most newer fixtures i have seen dont have this problem. the wiring scheme is different.

I am presuming you have a bi-pin lamp. I have had some sockets (lampholders, tombstones, headstones) that would cause something similar to this.

The sockets should be available at most big box stores. If not, your local electrical supply house should be able to help you out.

There are a couple of variations you need to be aware of when replacing them.
height; there are generally 2 different heights. Be sure you get the correct height or the lamp may not fit back in the fixture.

shunted or not shunted; a shunted lampholder has both of the terminals tied together inside the lampholder. Some ballast wiring situaions can use this, some can't. If you get the non-shunted, you can always put a jumper wire between the two contacts.

Now there are different types of mounting but there are a couple that are much more common than any other.

Be sure the ballast you have now has the same wiring as the original or that the shunted, non-shunted situation is correct for the current ballast.

A couple of other things to check as well;
voltage; if you have low voltage, this will cause you headaches

the switch; if the switch is bad and not making good continous contact, this also will be a PITA.