The delivered adapter hides the screws we used in the trial

I've left the new adapter unfitted. Our FR10 inspection-piece trial used one with room to reach the holder screws, but the delivered plate sits over them. Seller says it's equivalent and has been saying that for ten days. The pieces are light, so their replies keep coming back to weight. That's not the bit I'm stuck on. I need to change the holder without dismantling the whole tool.