Originally Posted by marciofs
The fixed sides of your two-bladed easel are likely okay the way they are. As mentioned above, there is usually a thumbscrew in the corner that allows you to set the size of the border. Make sure this is deep enough that the paper slips under the fixed sides.
Believe it or not, the fixed sides, even though they are a little bit higher than the easel surface, will hold the paper more than flat enough for enlarging. Contrary to what many think, if you stop down a couple of stops from wide open on your enlarging lens (usually the best spot anyway), there is more than enough depth of focus at the easel for a bit of paper unevenness.
I often correct for small perspective errors when printing by raising one side of the easel. I've raised the easel 2 cm or more at times and never had problems with depth of focus (I'm making 11x14 inch and 16x20 inch prints from 4x5 inch negatives).
My two bladed easels are the same as yours most likely and do just fine.
Best, und schöne Grüße aus Wien,