While aligning the take-up spool in the spoolbox of an upright player piano isn't a very difficult task, doing the job right can be more involved than simply changing the position of the stop collar.

First, understand that the primary objective is to position the spool such that when the music roll is tracking properly, there will be an equal amount of space between the left and right edges of the paper and the left and right take-up spool flanges. Here's a picture of what that look like.

While it might not be totally obvious in this picture, note that the tracking holes are open the same amount, the holes in the roll are aligned with the holes in the trackerbar, and there is an equal amount of space between the edges of the paper and the spool flanges. Only when all three of these criteria are met is the take-up spool properly aligned in the spoolbox.

Generally speaking, there is normally only one part in the transmission that is responsible for positioning the take-up spool. It is usually called a 'stop collar'. Here is a picture of where the collar is typically located.

This picture was specifically selected because it shows the stop collar set screw and the drive and pinion gears. The importance of these two gears will be discussed shortly. For the time being, just note that loosening the set screw on the stop collar will usually allow you to change the horizontal position of the take-up spool (either left or right) so that it meets the criteria mentioned previously. (See next paragraph.) Also, be aware that many take-up spools are 'spring loaded' such that loosening the set screw will allow the spool, the drive gear and the connecting shaft to move to the right. So, this means that when making the adjustment, you must hold the spool in place when re-tightening the set screw.

In some cases, it might not be immediately possible to move the spool to the left. In other cases, moving the spool to the left OR the right might cause other problems. Next we'll address these possible problems and the solutions.

   1.) Note the position of the drive gear. It is normally very close to the frame of the transmission, and in some cases, moving the connecting shaft to the left will cause the drive gear to rub against the frame. If that happens, it is necessary to loosen the drive gear set screw and reposition the gear. Normally, there should be about 1/16" of clearance between the frame and the gear.

   2.) Note the position of the pinion gear. It is almost touching the drive gear. In the above picture, the system is in the Rewind mode. So, the pinion gear should NOT be engaged with the drive gear. With this in mind, note that if the take-up spool (and the associated parts, i.e. the drive gear and connecting shaft) is moved to the right, the drive gear will make contact with the pinion gear. If this happens, it will not be possible to rewind the music roll. So, here again, the position of the drive gear must be changed.

   3.) If there is an excessive amount of space between the drive gear and the frame, it's possible to move the spool so far to the right that the pinion gear will not engage with the drive gear when the system is in the Play mode. And, here again, the corrective action is to change the position of the drive gear.

It should be fairly obvious by now that there's what's commonly known as a "sweet spot", where the pinion gear and drive gear will engage and disengage properly in the Play and Rewind modes.