Connect audio output to recording device
Manual here such as it is.

Disconnect microphone wires AFTER noting which wire goes where.
A photo that is detailed enough and sharp enough to allow you to tell is a good idea.
Putting a copy of the photo on disk somewhere with a file name that tells you where it is "is wise"
Emailing a copy to yourself using a persistent online email account (eg gmail and many more) with key words in the message and subject line is overkill and latterly often welcome.

Connect 2 wires to where mic went with a 100 uF electrolytic cap in one wire. 

Try connecting phone or line audio source to the above input - start with volume turned down, and turn up progressively while listening to result.

If level is far too high add two resistors to form an attenuator. Value shown below are a start - abut 11:1 attenuation.

Attentuation = R2/(R1+r2) if capacitor impedance is small compared to resistor values.
Making values too low (eg 10 Ohm, 1 Ohm) loads input excessively and capacotor impedance may be too high.  .
Making values too high eg 1 megOhm/100k causes impedance matching problems at recorder.
R1 and R2 could be a single eg 10k potentiometer with output at wiper.  







simulate this circuit &ndash; Schematic created using CircuitLab