Hi, I recently purchased a 2nd hand HTB-AR lens. However, the prisms moved when in transit (damage claim is currently active with UPS). In the meantime I have tried to replace the prisms although I'm not sure I've been totally accurate. Using the lens my images are trapezoid shaped with the image being wider at the top (particularly the top right) than the bottom. If I tilt the lens so as to correct it then areas of the image (particularly toward the top left corner) go out of focus. It's really frustrating. Can anyone offer advice?