Repairing an old Mitutoyo profilometer probe

Some time ago I repaired an old Mitutoyo profilometer 178-928D , which no longer has spares and which had broken the pin that transmits motion to the head holder; a calibrated shaft that moves left and right and which I hold in the following image (the pin / screw was in the center hole):

This probe has a very simple operation. The spindle that is coupled detects changes in a very similar way that is translated the marks in an old LP music disk, transmiting the movements caused by the roughness by a magnet and coil needle.

The shaft that moves the spindle is moved in a controlled manner with a step by step motor to an endless spindle, first the engine slowly forward in the measurement phase, and then quickly picking head to its starting position, all controlled from the profilometer which is connected with a cable with 6 wires (that is a seven or eight cable, but one or two are not used, as you can see in the following images after repairing the cable too):

Repairing a tape backup LTO 2 unit: HP Ultrium 448 with broken tape

In a unit Ultrium Fujitsu (HP) for backup, the tape had broken, being useless as the mechanism for capturing the tape was inside it. To repair the unit is complicated, recommended only to those who have already dealt above with similar mechanisms (VHS, glory times). 
To repair it is necessary to understand the method these units use (and many other models are based on the same principle), a curious way to save space by having a single drum in the cartridge and in the unit, where the tape passes from one side to another as information is stored, until it ends.

These LTO (Linear Tape Open) are optimized for capacity, and the latest versions, able to store 2.5TB of information in one cartridge that costs about 20 €, making it very competitive in terms of price and space currently.

After this brief introduction, let's go to the subject.