The unit has two plates that can be easily removed for maintenance and inspection. The top plate gives access to the cassette holder and the reverse side of some PCBs, and is held in by two metal retaining clips located towards the front of the unit and by two cross-head screws located on the back of the unit.
To remove the top plate:
1) Remove the screws circled in the attached image.
2) Pull the top plate straight upwards, away from the unit from the back to approximately a 45° angle.
3) Pull the plate backward (from the unit's perspective to release the retaining clips located at the front of the unit. One of the clips is partially trapped by one of the tabs on the front plate, thus some wiggling may be required to release it fully. Work gently but firmly to avoid damaging the front face plate.
Alternative link:
https://drive.google.com/file/d/14HC...ew?usp=sharing