Hammond Model A, Manual, Page: 108 / 298

When a preset key is depressed, the longer soft spring is forced downward and snaps
under a tubular rod which is part of the cradle. The cradle is constructed of two
tubes approximately 6- long and assembled 3/4 - apart. One tube is used as a
fulcrum, the entire assembly being mounted perpendicular to the preset keys. A
spring and bumper hold the cradle at a 60 degree angle toward the front of the
console.
Once a key has been depressed, the soft spring remains under the tube. It is backed
by the short stiff spring to give it sufficient tension to hold the key down. When
the next preset key is depressed, the cradle is forced down and outward, permitting
the previously actuated key to come up, but again locking the one last depressed.
If two preset keys are depressed at once, both will lock down. The cancel key with
its long stiff spring is then used and forces the cradle down, causing all preset
keys depressed to return to their normal position. As there is no locking spring on
the cancel key, it will immediately return to its normal position.
PRESET CRADLE RETURN SPRING
Earlier instruments had coil springs of various types to perform the function of
returning the cradle assembly to its rest position, and replacement, when necessary,
became rather involved.
A more durable spring has been devised, and is used on the later instruments.
It can also be used for servicing the earlier consoles.
Replacement is made as follows: If it is determined that a new return spring is
necessary, on either manual, the left hand end block of the manual needing the
replacement should be removed. The upper or lower manual assembly will have to be
raised to gain access to the wood screws holding this block. After removal of this
block, the end of the cradle assembly will be visible. Also visible will be the stop
felt and bracket assembly. This is a small angular bracket with a small piece of
felt rivited to it, mounted in a vertical position. Remove and discard this part.
Install the new assembly so that the felt pad is above the preset cradle, and the
flat spring is below the cradle, as shown in figure 16. Clamp it in the center of
the range of adjustment provided by the slot. Check all preset keys for operation,
and adjust the position of the new assembly in case any keys do not operate
correctly.
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