Amano CP3000 battery.
When to replace it:

• If the display is just flashing and the machine does not respond
• If it loses the memory when the power goes off
• If it is more than 3 years old
• We get fresh ones every two months, our batteries are “hot“.  
• Old batteries, old stock, are a waste of money.

How to do this: 

You will need the 700 key, and a small Phillips head screw driver

• Leaving the machine plugged in, remove the screws at the very top of the machine only (they hold it to the mounting bracket on the wall).
•  Lift it up and out, you'll see the battery. 
• Have a sharp scissors or razor blade handy
• Cut the nylon battery retaining strap - just leave it there as it threads through the case and isn't worth taking out for all the hassle.
• Remove the old battery, plug in the new one (red to red, black to black).
• Hang it back on the wall.  
• Switch the panel switch to PROG, and the printer will move to the ribbon change position. 
• Change the ribbon if it's light. 
• Put a few DROPS of WD-40 on the metal guide bar that the ribbon travels on.
• Flip the switch.
• Now your work is done.

Estimated time for a "newbie":  10 minutes
Call it day, you are a success..

We saw them hanging out, but not making eye contact...

• It was a warm summer night, there was trouble brewing, it was in the air...
• People were lurking outside the back door, sipping coffee, looking agitated.
• That's when I realized the time clock was not working, they were my people, and they weren't working.
• I knew the answer:  I had a bad battery.... I had to fix it, that's another story, another matter altogether.
• When it was all done, when the smoke had finally cleared, I found it here: