Action Lubrication in Instrument Construction & Repair Posted January 12, 2004 I'll post an article I wrote awhile back. I think that the old, older the better, Bastaris deserve recognition. Common Repairs The 30 button Bastari/Stagis will eventually have a problem with the rubber bushings, or sleeves, holding the buttons to the pad levers. The rubber will eventually get hard and the pad lever will wear a groove in the rubber where it bears on the lever. Thus the buttons will cock in their movement and tend to stick in their holes of the endplate. The first thing to do is to use model airplane fuel tubing rather than surgical tubing for the replacement. I use Aerotrend “Blue Line” silicone (www.aerotrend.com). I have experimented with two sizes of tubing; 3/32” ID (part # 1003,)and 1/8” ID (part # 1005). The 3/32 has an OD of 7/32”, while the 1/8 ID’s is ¼”. Either size will work, but I have found that the smaller seems to be best. There are some places where there can be a clearance problem with adjacent levers, so the smaller OD has an advantage. In order to get the best performance from the buttons one must understand the mechanics of the action. When pressing the button it should travel perpendicular to the end plate. However the valve lever moves in an arc, so the attachment of the button to the pad lever must act not only as a hinge, but the attachment to the button shaft must have some flexibility to move slightly along the axis of the lever as well. Otherwise the button would also move in an arc and bind in the endplate. With this in mind the length of the sleeve should be just long enough to hold the button on the lever. Too long a length will hold the button too tightly to the lever and not allow any motion along the lever. It should not be enough to let the button slide on the lever, but shift a little using the flexibility of the tubing. Again, too long a length will compress the tubing limiting that flexibility. While replacing the sleeves, it may be noticed that some of the lever arms have been bent sideways as a result of the cocking of the buttons. Also, the arms themselves may wobble due to the U bracket holding the axle being too wide. A good quality pair of needlenosed pliers will be necessary to effect the adjustments. The potential dismantler must use a proper fitting screwdriver. The preferred type is what is called “hollow ground”. A standard flat screwdriver has tapered sides, and often the end is often not absolutely flat and square either, even when new. The optimum way to make one is with a grinding wheel, hence the name hollow ground. However one can make one with a fine toothed file. The trick is to draw the end of the screwdriver along and over the file (which should be securely mounted in a vise) rather than moving the file against the screwdriver. I also found that if I clamped the shaft of the screwdriver in visegrip pliers and moved the screwdriver against the file by means of the visegrips hanging below and against the file I was able to get the best results. Further, I hardened the tips, since nothing is more damaging to a slotted screw head than a screwdriver with a soft tip. There are commercial chemicals for hardening, but heating the tip cherry red and dousing in oil is adequate. Bellows leaks are generally not that big an issue. By using liquid electrical tape (page 566, West Marine catalog), repairs can be readily effected, with a light coating on the inside of the bellows. If there is a large crack or tear, the trick is to lightly saturate a piece of handkerchief cloth with the liquid tape, then apply to the inside, after taping a piece of food plastic wrap to the outside in order to keep the goo on the outside. A simple jig is in order to keep the bellows extended during this operation. (see attached) Another source of leaks is the gasket material around the bellows end where is fits to the reed and action frame. A recommended replacement for the common “string”, is self-adhesive, closed cell vinyl foam weatherstrip, 1/8” (T) x ¼” (W), available from your local hardware store. Cleaning the reeds is best done with a strip paper drawn between the reed and the plate.