When the hook begins to lift the bin off the ground, what is the distance between the bin hook and the rear of the truck. To maximize weight lifting capacity this distance should be as minimal as possible and the arc of the bottom front of the bin should just clear the rail/roller as the lift travels through its path.A guess of what the issue is (without seeing more photos) would be that the lift is installed to far to the rear. Can you show some side view photos? It's a pretty simple statics problem but I would need all relevant dimensions to help you work it out. I'd also need the empty front axle weight.