Thanks Mike. I was hoping that other Colorstar users would add their voices.
From what you have said, Mike, you don't have the same cover either so my mystery cover remains a mystery cover. I think that you are saying that for measuring you use the 7x7cm diffuser material sheet under the lens but instead of placing the clear spot cover in the middle of the projected neg for full integral measuring you move the the clear spot cover around the neg to get several measurements and this gives a good print. Have I got this right?
You don't use the diffuse cover 104 as shown by hka and use that in several positions on the projected neg?
PS Do you use the Nova sytem for processing? maybe you can have a look at my other two threads. I am having difficulties with safelight fogging and potential age-fogged paper as well. PE has given some help there but I won't say anymore here otherwise the threads get mixed up.