Help with Pavelle 401 and Durst Laborator 1000

[photonsoup]

So I set up the Durst, I put on the Pavelle head because it came with some negative carriers that would fit. I have the original condenser head and condensers, but haven't found a negative mask for 4x5 in the Otoneg2.
The light projected onto the base is very uneven (dark in the corners)
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There is a drawer with two pieces of plastic presumably to diffuse light. When I pull it out this is what the projected light looks like
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Here's a picture of the drawer and a 4x5 negative carrier
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[photonsoup]

The Pavelle sits directly on the negative carrier. There are two legs with rubber feet that lift the head off the base (red arrows pointing to). the slots in the carrier fit around the feet. This picture is looking directly into the Pavelle head.
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So am I missing something? Is there supposed to be a mixing chamber between the Pavelle and the negative? Is there a better way to defuse the light?

If I get the light evened out, does anyone have a chart comparing the numbers on the red dial with multigrade filters?

Does anyone have a copy the manual for the Pavelle they would be willing to share?

[quine]

Yes, there should be a mixing box. It basically fills the inside of the head with a 45-degree slope opposite where the bulbs project inwards. Mine looks like it is lined with something akin to white foamcore.