T5 bulb light on one end for a second (ATI Sunpower)

[Jarzy]

I bought a 7year old ATI Sunpower 4x54W as a temporary lamp. It's pretty used up but cost like 40 bucks and almost all was working. Almost. 3 bulbs light up nicely. The 4th one light on one end for a second or 2 and goes off. I've changed 1 ballast to a new one since at the beginning only 2 bulbs were working. I've also changed 3 bulb sockets to new ones to eliminate one of the possibilities. The reason I changed 3 sockets (2 from the faulty bulb and 1 from the working one) is one bulb is perfectly fine. It kinda seems one end of the faulty bulb holder is not connected properly or am I wrong? I've changed different bulbs to the faulty slot, scraped off every cable's end to eliminate rust. Nothing seems to help. dang bulb lights on 1 end and that's it. Should I change the 2nd balast? Seems kinda pointless since the other pair is working fine :/ Help!

 

[Lbrdsoxfan]

Ballast... Or if you didn't replace bulbs, likely those.

 

[Jarzy]

Ballast... Or if you didn't replace bulbs, likely those.

Are You absolutely sure? The lamp Has 2 ballasts. 1 pair is ok. Is it possibile one bulb is forint while the other is not? 1 ballasts was replaced. Bulbs are fine-they all light up.