The fixtures are older T-12, 8', 2 lamp, single point ends. There are many at this location but this one is not working for me. First it wouldn't come on at all. I replaced the ballast with a new one, from Loews, commercial instant on ballast that fit the requirement. It would flash on and then shut down. Tried a 2nd ballast. Same result. Have electric to the ballast and to the two sockets on the one end (both the red and blue wires). But once it shuts down I still have juice at that red and blue ends, but nothing at the other end (the yellow wires). What do I do next other than replace the entire fixture?
You're much better off with the (did you notice, much lighter) electronic ballast. Instant start is fine, since it's the only type possible with 1-pin ends.
There are only 4 parts to a fluorescent lamp: Chassis, lampholders, ballast and lamps. You just eliminated ballast. Lamps, I'm trusting you here. That leaves lampholders.
Look at the lampholders closely, make sure they are intact and the jumper between the yellow lampholders is intact. 8' 1-pin replacement lampholders can be had for a couple of bucks, I replace them all the time. (4' 2-pin lampholders are like 60 cents.)