The service manual is a good quality scan of the Panasonic NV-850, which is electrically identical to the Philips VR 6920, but mecanically just nearly.
The service manual is a good quality scan of the Blaupunkt RTV-404, which is electrically and mecanically identical to the Panasonic NV-830.
Text excerpt from page 4 (click to view)
HOW TO OPEN THE DISC TRAY WHEN POWER SWITCH TURNS OFF
Insert a tapeing driver into the aperture of the unit bottom, and turn in the direction of arrow (to OUT direction.) * To close the disc tray, turn the driver in the reverse direction(to IN direction).
NI
OU T
Tray
NOTE FOR MAIN GEAR INSTALLATION
5 Rotate the MAIN GEAR until the portion that has no gears, of the MAIN GEAR is aligned with the shaft of the GEAR (REV). Then insert the GEAR (REV). 6 Stopper washer (5)
Projected portion
3 Install the MAIN GEAR while aligning the protrusion of the MAIN GEAR to the cut-off of the ENCODER. 2 Set the cut-out of the ENCODER to the right when viewed from the front view. A
1 Rotate the GEAR (U/D) to the arrow A direction.
SHAFT
B
Front view
B 4 Open the SET LEVER and LOCK LEVER in the direction of the arrow B, and push in the MAIN GEAR.