As to the function of the various controls in front of the keys:

The lever on the far left is 'manual sustain'. It works like the right pedal on any regular piano (the sustain pedal). Typically labeled "Loud", it was installed so that when the unit is being pumped with the foot treadles, the sustain can still be used in the appropriate places to enhance the quality of the music. (Most Aeolian players also have an 'automatic' sustain mechanism which operates the sustain pedal in response to perforations on the music roll.) The "switch" (in the Spool Box) above the round 'on-off' button is most likely the 'On-Off' switch for the Automatic Sustain Mechanism. Typically it will be marked "On" "Off", but it might have the word "LOUD" somewhere close by.

The two push-buttons next to the Manual Sustain Lever are the Bass and Treble Soft controls. When activated, they operate a pneumatic device which pulls the hammers closer to the strings in much the same way as the left pedal on any regular piano (the soft pedal). The main difference between the soft pedal and the push-button soft controls is that the soft pedal pushes the entire hammer rail closer to the strings. The Bass and Treble soft control devices 'pull' a secondary hammer rail which is split in the middle so the user can reduce the volume of the music in either the Bass or Treble registers independently.

The final lever (to the right of center) is the Tempo Control. This control allows the user to change the speed at which the music plays. It usually has markings of "0" "70" and "110" or "120". It is, in effect, the speed gauge. Although not usually very accurate (it's not easily calibrated) except at the "0" and "70" marks, it should be utilized to select the correct tempo indicated on the player piano roll (near the beginning of the roll).

As for the controls inside the Spool Box:

Inside the Spool Box, there is another lever (towards the right hand side) which is marked "Play" "Re-Roll". As those names imply, setting the lever to "Play" allows the unit to play the music or "Re-Roll" or rewind the roll. Most Aeolian Sting players also have an automatic Re-Roll mechanism which is triggered by special holes at the end of the roll. When triggered, it rerolls the roll automatically. And at the end of the rewind cycle, there is another device which senses that the paper is no longer covering the brass tracker bar and shuts off the electric vacuum pump. This function only comes into play when the unit is used electrically. The auto 're-roll' function works whether the unit is foot pumped or operated electrically.

Finally, there may also be another knob on the right hand side of the spool box marked "Low" "Med" "Hi" or just 'Low' and 'Hi'. This is a three position volume control which works in conjunction with the electric vacuum pump to control the general volume level of the unit. Here again, as with the Tempo control lever, the amount of control is, to a degree, unpredictable. On some units, the degree of change is fairly pronounced, from very loud to medium level. On other units, there is very little change from one extreme to the other. Usually this has more to do with the condition of the player mechanism in general than it does the ability of the control valves to control the level of vacuum created by the vacuum pump.

Musically,
John A. Tuttle (John A Tuttle)