Not sure what you're talking about. Butt plate screws are accessible from the back of the action, in between the damper levers, not the front. The screws that hold wooden flanges or Billings flanges to the action rail are the (butt) flange screws, not butt plate screws. Butt plates are found in two types of upright actions: 1) old upright actions that have brass rails fastened to the main action rail -- see bottom of page 134 in the Schaff catalog. These brass rails have tabs, or tongues that stick up vertically, with a groove in them for the center pin. A butt plate (approximately 1/8" x 1/2", or 4 x 12 mm) clamps the center pin to the tab by means of the butt plate screw, which is quite small -- about 2 or 3 mm in diameter by maybe 10 mm long -- much much smaller than the wood screws for wooden flanges. Also, it's a machine screw (not tapered like a wood screw). You need a long narrow screwdriver to access these. A small screwdriver with a 1/8" wide blade and a shank not much thicker will work, but the so-called Kimball screwdriver in the Schaff catalog, page 40, #4106, is better. The brass rail is threaded and the screw goes in from the rear (damper side), although there are some oddball actions where the butt plate is threaded. There are also screws that hold the brass rail to the action rail. These would have to be extremely loose to cause any malfunction in the action. To tighten these, yes, you usually have to push the jacks to the side. They'll usually yield enough, but be careful -- you could break a wippen flange if you push them too far. 2) some (usually) Asian uprights (Yamaha) that have Schwander-type butts, where the hammer return springs are part of the butt assembly and are retained by a loop of thread fastened to the butt flange. Some of these have "standard" wooden flanges with a full circular birdseye, and some have only a semicircular birdseye with a butt plate. Again, you tighten the butt plate screws from the back, between the damper levers. This type of butt also has a flange screw that holds the flange to the main action rail. The flange screws can be tight, but if the butt plate screws are not, the hammer can still be wobbly and the center pin can "wander," or work its way out of position. For "regular" flange screws on wooden or Billings flanges, you use an action screwdriver -- Schaff # 34 or 35, page 41. You nudge the jack aside with the tool and the lip or edge or notch or inset or whatever it's called, helps hold the jack out of the way. There used to be one available where the rear notch was flared, rather than a right-angle notch, which prevented snagging the jack when removing the screwdriver, but I don't see it in the catalog. You could modify #35 by filing down the sharp corners on the "back edge" of the blade. With either type of butt plate, if the screw or plate is missing, the entire hammer assembly will be about ready to fall off and so wobbly it won't function. Yes, there's a little nub on the brass rail that helps (not much) position the butt plate in place. You also need a butt plate inserter, Schaff #128, page 53, for holding the butt plate in place while you get the screw started. This is done before you position the butt onto the tab of the brass rail. You have to feel the center pin "snap" or "click" into the groove on the tab, before you tighten the screw. Hope all this helps. Still not sure exactly what problem you're having, unless it's an oddball action with some screw/butt plate arrangement I've never seen. ---David Nereson, RPT