So, after a more throughout check, I’ve determined that the issue lays solely with the viewfinder extension. Since the prongs on all of the ARRI viewfinders only allow for two different positions (180 degrees in one direction and 180 degrees in the other,) I tried both positions with the extension and both positions with only the standard viewfinder.
When I used the extension, the circular obstruction appeared on the RIGHT part of the frame, but the left side of the frame was clear (see “A” below.) When I removed the extension, turned it 180 degrees, and attached it again, the obstruction appeared on the LEFT side of the frame and the right side of the frame was clear (see “B” below.)
When I used the exact same process with the standard viewfinder, I had no issues. It’s almost as if the barrel of the extension is partially closed or something.
Here is a picture of the viewfinder extension:
And here is a closer view of what looks like two small levers.
I’m not sure if those do anything and I don’t want to start unscrewing things. So if anyone can offer any advice, I’m all ears. The seller is very fair, so the worst-case scenario is a refund. But I’d rather solve the problem.
Thanks for any help.