I just bought 8x10 enlarger and having a hard time to adjust alignment of the he ad of the enlarger. When one part of image is focused , the other part of image is not focused on easel. Someone told me that there is a product called "align ment finder", but I've never seen it before. Does anybody know where to get the product and how the product work?? I am using 8x10 glass neg. carrier and going to make about 30x40 inch image size. thank you sugi