Sony MZ-R91 MiniDisc Player

Sony MZ-R91 MiniDisc player/recorder (blue). Quantity 1. Used.
* No other items or accessories are included in the sale *
** This sale does not include any way of powering the device. Unless otherwise stated, this device requires a special kind of rechargeable 'gumstick' battery that is inserted into the device. Please either ensure you are familiar with this requirement in advance, or reach out to us if you are unsure. **

Summary:
Sold for Parts Only / Not Working.
This is a DAMAGED device and may lose some or all of the functionality it had at the time of testing. Recording fails and erases discs.
All other tested functionality OK. Almost perfect cosmetic condition.

Product Condition (Appearance):
Display Panel : No noticeable scratches.
Front Face : No callouts.
Sides : No callouts.
Rear Face : No callouts.
Internal Battery Compartment : No callouts.
No noticeable dents or signs of crushing.
All external facing screws present and tightened.

Product Condition (Functionality):
Recording fails and erases discs. All other tested functionality OK. Almost perfect cosmetic condition.
See test results and photographs for detail.

Player / Recorder Unit:
Sony MZ-R91

Power Via Rechargeable Gumstick Battery : OK *** Rechargeable gumstick battery is not included in the sale ***
Power Via External AA Battery Case : OK *** External AA battery case is not included in the sale ***
Power Via AC Adapter (3V, 500mA) : OK *** AC adapter is not included in the sale ***
Rechargeable Gumstick Battery Charging Via AC Adapter (3V, 500mA) : OK *** Neither rechargeable gumstick battery, nor AC adapter are included in the sale ***

Audio Playback : OK - listened to over an hour of audio with no issues
Audio Output : OK

Recording Via External Microphone (Analogue) : NOT TESTED
Recording Via LINE IN (Analogue) : FAIL
Recording Via Optical Cable (Digital) : NOT TESTED

Stop / Charge : OK
Play : OK
Pause : OK
Record : OK (Button works but recording itself fails)
Previous Track : OK
Next Track : OK
End Search : OK
Volume Down : OK
Volume Up : OK
Menu / Enter (Jog Dial) : OK
Hold : OK
Synchro Rec : NOT TESTED
Track Mark : OK (Button works but recording itself fails)

Disk Insert : OK
Disk Eject : OK

Device Setting Details:
AVLS set to OFF
MEGA BASS set to 0
AUDIO OUT set to Headphone

Product Information:
The Sony MZ-R91 was released in October 1999, just eleven days after the MZ-R90. It has both playback and recording functionality. 
It has an aluminium body (the MZ-R90 has a magnesium body).
At the time of release it was claimed to deliver the world's longest continuous playback / recording performance for a portable MD device. When used with both a gumstick battery and AA/LR6 dry cell battery, it was said to be capable of approximately 29 hours of continuous playback or 14.5 hours of continuous recording.
It does not have MDLP functionality. 
It weighs 110 grams without a battery or disc installed. 
It has a 3.5 mm headphone jack for audio output.

Hopefully this information is clear and covers everything you need, but don't hesitate to reach out if you have any questions.