The battery holder in this Roland TR-808 Rhythm Composer was broken and needed replacement.  It was missing a contact spring and also had oxidization damage.

Without a working battery holder, you can't save any of the rhythm patterns or drum tracks that you create.

The battery holder assembly is attached by the two mounting screws shown circled in this photo.

Before taking out the screws, first open up the TR-808 so you can access the inside.

Refer to the top three photos on the first page of this Repair Story for instructions.

You'll then see the battery holder assembly attached to the bottom chassis (right).

With the two mounting screws removed, turn over the battery assembly.

You'll see two more screws that attach the battery holder to its mounting frame (right).

Remove the attachment screws as shown here.

Then attach a new battery holder to the frame using the same screws (right).

You can order these brand new, TR-808 battery holders here:

Roland TR-808 Battery Holder

Next, unsolder the old battery wires from their lugs on the TR-808's power supply.

Then solder the new battery wires to those lugs.  Make sure the new red wire goes to the same lug as the old red wire, and likewise for the black wire.

Remount the battery holder assembly to the bottom of the TR-808 using the same mounting screws you had removed.

The installation is now complete and you can close up the Roland TR-808.