Won't play recorded cd's

Check its laser pickup assembly for any dirt or dust. Click here for more details

It does not look like this device might play any CD-R or MP3 and is very unlikely that can be modified because of the way it was design. It does not like to play copies only original CDs.
My suggestion will be to buy a device that is compatible with CD-R and MP3 as well.
That could be a cheaper way then trying to modified it.

bin the damn shitzer

Having just removed three discs from an identical unit which also jammed, I will say how easy that was. I do not know if the unit will now function when reinstalled in the vehicle.

Remove the unit from its mounts, remove the outer "frame" (if fitted), remove the two #2 phillips pan head screws from the sides holding the face to the chassis, remove the four #0 phillips screws (black, flat head) from the top and bottom of the face plate.

Slide the face plate off and carefully handle it while tethered by its ribbon wire.

Turing the unit upside down, peer into the opening and observe the disc, gently press the carriage away from the top of the unit (now the bottom, as it is inverted) and allow the disc to be freed, simply pull the disc out.

If there are multiple discs stuck inside, oberve the large metal gear just inside, carefully rotate the gear to actuate the loading mechanism as needed to release addtional discs.

I suggest you should give your audio player for general service..!!

The CD45z does not play MP3's ....Nak is about SQ ...since MP3's are poor quality ...this doesn't fit with what Nak is about.

COMMON PROBLEM
OPEN IT UP AND REMOVE YOUR DISC AND THEN THROW THE PLAYER AS FAR AS YOU CAN.

VERY COMMON PROBLEM
THE BEST THING TO DO IS THROW IT AWAY

Try this link. It offers resistor changes which are designed to fix your problem of inability to play any CD R. on that model Nakamichi. jacknz0 http://home.cogeco.ca/~niteowl/Nak_MF51.jpg

COMMON PROBLEM
THROW IT AWAY