Keyboard Rubber Rolls
The rubber rolls are held on shafts which extend through the cam frame. The right end of the shafts run in bushings which are held in the cam frame by a screw extending through the cam frame bracket into the shaft bushing. Two kinds of rubber rolls may be obtained: corrugated and ground. The rolls must be kept free from oil at all times. About once each month they should be removed and washed with soap and water to remove all oil, and freshen the rubber. The rubber roll may be livened up by the use of course sandpaper, rubbing from end to end and turning the roll so it does not become flat. The roll should be washed after using the sandpaper to remove the small particles of rubber that may be adhering to the surface.
If the rubber rolls become worn until they are grooved where the cams operate on them, or if they become hard with long use, they should be replaced with new rubber. Good, live rubber rolls have much to do with quick, even response of the matrices.
A rubber roll that is in good shape with the exception of a groove or two, can be used by cutting out the worn parts and placing in a good piece of another roll and fitting it to the shaft. Save parts of old rubber rolls for this purpose. They at least may be valuable for emergency patching, until a new roll can be ordered from the factory.
The rubber roll shafts are driven by friction, so that if anything binds unduly the shaft will stop, preventing damage to the rubber.
To replace a rubber roll, remove the old roll, polish the shaft, using care to clean thoroughly. A new roll must fit tightly and if the shaft is not clean and smooth, it will be hard to force the new roll on. Place the shaft in an upright position, start the end of the roll through the pulley end of the shaft. Place your thumb or hand over the other end of the roll to hold in the air and push down on the roll until it is in position.
On the later models the shaft carries a collar, pin, and oil collar on each end. This assembly must be removed on one end before the roll can be removed. The collar is held to the shaft by a taper pin and the oil collar forced over the top of the pin and collar. This oil collar must be pried off before the pin can be driven out.
Keyboard Troubles
Many of the mechanical troubles will be found in the keyboard, such as continuous response or non-response of matrices.
The keylevers sometimes get gummy or sprung to one side and bind on the frame, causing a continuous response of matrices. Another cause for continuous response may often be traced to some foreign substance such as metal shavings or dirt getting between the keylever and the frame.