[Yaesu] FT-415 memory backup?

[Michael Tortorella]

Good evening to the list,
I hope someone can help me figure out why my FT-415 will not hold memories
after power off (even for a short while, like seconds).  The radio programs
and operates normally, but the memories disappear when I power off.  I
opened it up to see if there was a backup battery that needed to be replaced
but I could not find one.  Perhaps someone has a lead on a service manual or
page that describes this issue?
aTdHvAaNnKcSe and 73
Mike W2IY