I got the plate from www.hayspear.com. It appears to be a quality plate. It appears that the pins move up, compressing the springs and popping out. The handles stay in place. I am thinking maybe I need to put more preload on the springs. That way when the pins try to push up they will coil bind the springs and not be able to come loose. When you say the angle of the pins are you talking about the cut angle of the end of the pins? The pins appear to be parallel to the surface that goes against the bucket. Hayspear.com knows that they are doing so I cant see them doing it wrong. The bucket was an old style that I modified to meet the SAE universal specs. I got the angles dead on. I measured the bucket compared to a blank plate I have laying around. The depth (horizontal distance) of the pin slots from the face of the plate is exactly the same. The only thing that is different is the angled plate that the pins go into is a little larger, measured vertically than the blank plate.
I have seen this on two different machines. Both were caused by wear in the hole where the pins from the quick-tach engage the quick-tach plate.
With the bucket attached to the quick-tach, how far to the pins extend past the edge of the quick-tach plate? Also watch the springs as you close the handle. The pin should engage the quick-tach plate with the tip of the pin protruding a small amount past the quick-tach plate.
The sooner the pin makes positive engagement, the more the spring has to compress for the handle to be in the latched position.
We fixed both of them by welding a bead on the quick-tach plate where the pin touches the plate. Both buckets had some wear. When you put down pressure on the cutting edge the base of the bucket would start pulling away from the quick-tach. It seemed like once it started to move the pins would keep retracting.