low voltage halogen light problem

[gabagoo]

I am sorry if this is long winded but I have been suffering with this dilemma now for about 4 years and need some knowledge.

We bought 2 hanging low voltage halogen lights that hang above the island in our kitchen. The fixture is a nickel finish looks kinda like a torpedo and has small holes around the top of the fixture that allow light to pass through from the rear of the halogen and originally it was a pink glow. My wife saw that some of these lights had a blue glow and I found them and put those types in. The bulb was different from the originals cosmetically with some kind of silvery surrounding and a glass shield to protect the bulb.
After about a year or so one of the lights went out and I replaced the bulb but it still did not work so I started maneuvering the bulb around in the socket and it flickered and I found if I did not put it all the way into the socket it stayed lit. Shortly there after the other light started to do the same thing and again found the same problem. I got them both up and working for about 6 months and then the original one started to fail again. You could see it flickering a bit at times and then it would stop working. Again I monkeyed with the bulb and now I found I had to spread the 2 metal prongs slightly and it made a tighter fit and the light seemed to work again.
Fast forward another 6 months or so and again the same light stops working. I tried spreading the prongs again but the ceramic insides fell apart. Got a new bulb tried again but now the light stays lit for about a minute or 3 then fails. When I have my hands on it I can feel a vibration. Yesterday after 3 months of the damn thing not working I got motivated again and started playing with it. I went to see if I had any bulbs and only found one of the older ones that gives off the pink backlight and I just plugged it in and voila it works. No spreading of prongs or half in the socket.

So now I am wondering if these two different bulbs could be the problem all along. I went to Lowes this morning but nobody there understands this problem and has any knowledge if there is indeed a difference in the two bulbs.

I decided I would find a forum and see if I can get this problem solved and find out what the difference is in the bulbs.
Any help you can give me would be appreciated.
Thanks

[adnadeau]

It sounds to me like a heat problem. 12V Halogen fixtures are rated for a maximum bulb wattage. Any bulb with higher wattage will generate more heat and the socket prongs and bulb prongs will oxidize, which causes intermittant operation. I think the pink glow indicates a lower wattage bulb than the blue glow bulbs; the hotter a bulb filament gets, the whiter the light. Also, if you did put higher wattage bulbs in the fixtures, the transformer that feeds those fixtures may not be designed to deliver that much current (higher wattage needs higher current for the same voltage). You can also measure the bulbs with an ohmmeter to see if the filaments are any good. Use 300 to 500 grit emery cloth or fine steel wool to clean up the bulb pins.

[gabagoo]

Yea possibly the blue bulbs create more heat. I will stick with the pinkies from now on. Ironically new years eve we went to friends who had the same 3 lights hangimg over the counter and one of them was out and he showed me how he has to wiggle the bulb around and then it turns on for a few minutes. Maybe it's the fixture itself.