yes, the bearings they use aren't good and don't last. However, you can still run them with bad bearings and all they do for a while is get noisy. I'd think you'd know if bearings were your problem and it wouldn't behave the way you describe without being really noisy too.

I just hate to see guys blame a good motor for what is really a fuel delivery problem. I think a lot of engine manufacturers are tired of debunking tank/fuel line problems too. If you've already done what I said, then bravo. If not, I think you owe it to yourself and the motor to try just running a fuel line directly to your carb from the fuel jug and see what happens.