Beogram 4002 (5514): Rebuilding the Arm Lowering Mechanism and the Tracking System

This Beogram 4002 (5514) had a completely stuck arm lowering mechanism. The lubricants had hardened to a degree where I needed to use a screwdriver to pry the linkages from their pivot pins. This is a frequently observed phenomenon, which is easily fixed by cleaning and lubricating the mechanism. This shows the solenoid and damper with linkages before I took everything apart:

This shows the parts spread out on my workbench:

This video shows how to rebuild the tone arm mechanism in detail. After putting the mechanism back together with fresh lubricants, I moved on to the damper to arm linkage. This shows the arms from the back. The linkage sticks out in the back under the yellow paint  marking:

To lubricate its pin the sensor arm needs to be extracted:

This linkage was also stuck and it can off including the pin on which it pivots:

After separating the pin from the linkage I glued it back in with a bit of epoxy and then reinstalled the linkage with a bit of silicone grease. This video shows how to get to the damper to arm linkage and re-lubricate it. Then it was time to put the sensor arm back in and align the arms to be parallel to each other and perpendicular to the carriage rods:

This concluded the restoration of the arm lowering mechanism, allowing me to move on to the tracking system. I usually install my SMD LED based light source to replace the original incandescent bulb assembly, which is not available anymore. LEDs are very long lived, so this promises trouble-free carriage operation for a long time.  I also replace the usually wobbly and/or cracked plastic carriage pulley with a precision turned aluminum unit, which can be had from Nick of Beoworld. I'll be happy to get other aficionados in touch with Nick, just send me an email. This shows the original parts in place:

After removal of the original bulb housing the tracking system aperture is visible:

This shows the 3D printed replacement part together with the original bulb housing:

My part has an integrated intensity trimmer, which enables a straight forward fine tuning of the tracking feedback sensitivity.

Here is an impression of the installed parts:

Pretty, isn't it?? I will adjust the tracking system sensitivity after I rebuild the PCBs.