I recently purchased a Beattie Intenscreen on eBay for my RB67. The Buy it Now price was under $50.00 and so I jumped on it. Little did I realize how teeny tiny and miniscule the 4 screws are that hold the spring bars in place. Fortunately the screen came with installation instructions which put you on notice to be careful when handling the infinitesimally small screws. Think the size of a pinhead. In order to reduce the possibility of one of the screws falling off the table I used the lid from one of those Styrofoam ice chests. The lid is about 2 inches deep. Also, being white, it is easier to find the black screws once you have removed them. Once removed they will not roll out of the lid. To make life a little easier I only removed 3 of the 4 screws. That may not sound significant but. considering it took about 20 tries for each screw to get it back in, it was worth having one less screw to, well, screw around with!
You will need a set of those very small screwdrivers that one uses for similar delicate work. You will also need a pair of needle noses tweezers (the smaller the better). The tweezers I have were a little too big thus making it harder to line the screw up properly with the threaded hole.
Also, when you remove both parts of the old screen keep it to the side exactly the way that you removed it. This way you look back at it to make sure that you are installing the new screen in the same way.
Finally, have a steady hand and lots of patience.