As found, non working, more later

First,  when received the handle was damaged in shipping. I have hope to find a replacement possibly from a parts machine beyond restoration..
Since I have the entire handle, I made a serious effort to restore and strengthen it.  (see the result later)
Moving on, I evaluated the machine as it stands

There is a tension roller on the chassis that positions the tape on the playback head, that is missing, though the pin that would hold it is there.
(without the tension roller the player will not work!)
The assumption is the roller on it was made of some sort of plastic material and it broke and fell out ot the machine.
The drive belt is also stretched and needs to be replaced.
I tested the player using a bench power supply, finally I tried it with the Panasonic adapter that came with it.
It turns out the Adapter is incorrect for this model, supplying only 6 volts instead of the 9 volts the player requires.
I almost forgot, the battery compartment damage

The final step will be polishing the cabinet plastic
There is a label on the cabinet top right  and what appears to be a missing label on the left top area
So far I have not determined what may have been there.

Time to move on. I removed the 4 cabinet screws and opened the case. (it's a tight fit)
It MUST be lifted from the bottom and tilted forward to open the case or the volume control can be damaged.
The first thing I noticed, was the  special circuit board used.
This is one of the first uses of printed resistors on a circuit board instead of individual through the board resisters.
This type of pcboard  was discontinued later because of the issue finding and replacing failed resistors.

I removed the 4 red chassis mounting screws (1 on the pcb by volume control).  Panasonic major parts are generally mounted with red screws for easy identification.
As suspected, the drive belt was a bit stretched, and was replaced, it's a narrow flat belt .
(Approx., 9.5-9.7 " such as  EVG FRX 9.5 or 9.7)

The belt is replaced by removing a screw on one side of the capstan bracket, while slipping the other side out of a notch in the chassis.
At this point using some emery paper the polished area of the capstan was removed, along with cleaning the head.
On 8 track player design it counts on the tape to be pressed against the capstan  usually using a rubber roller inside the cartridge.
In later cartridges, I believe to save money, hard rollers were used, in my opinion a big mistake.
Without perfect 8 track tension, and a non polished capstan on the player the tape it may slip.
The setup on 4 track tapes that came before these, is totally different which incorporate a rubber roller in the player that enters the cartridge to press the tape into the capstan.

Here is the actual schematic for those interested.

As suspected the lock lever assay was damaged, missing the nylon roller that helps lock the 8 track cartridge in place.
After looking at a few of these players, I believe this to be a common failure. At this point it may go un-noticed by owners.
Without that roller the player may still play most 8 track cartridges or by repositioning the tape.
I had to come up with a similar size roller for the lock lever, once installed cartridges were more stable.
Finally I replaced the negative battery contact springs and cleaned the positive contacts.

Re-assembly and final cleaning , polishing after the handle repair completes the repair

See the result here

(Until I find a replacement handle)

If you have any questions ask