This rotary switch allows you to switch tracks. In the "D" position, both tracks are played simultaneously. Unfortunately, the paint is already chipping off here a bit...

"Under the hood" of the TK 23 L, it looks similar to the other tape recorders in this series. After all, why should Grundig reinvent the wheel for every device? Additionally, the similar layout of the mechanics has the advantage that many parts can be exchanged between devices. In the case of this TK 23 L, the motor was extremely stiff. Therefore, I first removed and cleaned it, as well as applied new lubricant. Now, it runs smoothly and almost silently.

The fan blade with pulley is attached to the motor and secured to the motor shaft with a spring. Attaching it can be a bit fiddly. The best way to do it is to block the motor shaft and turn the pulley against the direction of the spring winding while pressing it onto the shaft at the same time.

A look at the heads and tape guides of the TK 23 L. The former are a bit worn out, but recording and playback are still clear and distinct. On the far left, you can see the contact for the automatic tape end shutdown. The plastic bearing for the capstan shaft can be easily removed for cleaning and lubrication. The volume control is not original to this device, as can be easily seen. The tape guides and pinch roller had to be thoroughly cleaned of tape debris.

The bottom of the device looks almost the same as other devices in this series. Significant differences between the Grundig devices can only be seen on the circuit board. Additionally, different motors were installed in the devices. If you look at other devices like the TK 19 L, you can see significant differences between the motors.

The circuit board of the TK 23 L has a structure with four tubes, while simpler devices like the TK 14 L are equipped with only two tubes (in addition to the magic eye tube EM84). The switch for recording and playback at the top of the image had to be made operable first.

This is the typical Grundig design that runs throughout the entire product line. On the left side of the image, you can see the power supply, in the middle is the motor, and higher up on the right is the output transformer. To the right of it is the electromagnet for automatic tape end shutdown. The contact tongues on the record button are used to switch between the three different recording modes (automatic or manual recording level control and trick recording for overdubbing without erasing previous recordings).

The fuse holders of the devices are often popular targets for corrosion during storage in not entirely dry environments. Therefore, they should always be thoroughly cleaned, especially if corrosion marks are already visible.

The contact blades of the aforementioned record button. By rotating it before pressing, the different contacts are activated and the desired recording function is selected.

The case and front panel of this TK 23 L also had to be thoroughly cleaned. The same applied to the carrying handle.

The device during a test run, specifically during a test recording. If you take a closer look, you can see the "swinging" magic tape. This can be used to check and control the recording level, especially when manually adjusting the recording level. The knob for switching the track was still missing in this picture.