Running 4 bulbs in a 6 Sunblaze t-5

[Loids]

I think there is one ballast in these, but maybe they're run off individual ones like the strip lights. I really dont want to run with 6 bulbs, electricity is getting too expensive for what its worth. I dont want to open it up and void whatever possible warranty there is. Does anyone have experience with Sunblaze 46 T-5? I havent ever let a bulb burn completely out but what would happen if i ran it off 4 working and 2 burned out bulbs? I had the thought of modding it by using the reflector and adding individual ballasts so I could independently control them. Any input on this is appreciated