[sdiy] battery replacement Linn drum

[Rude 66]

On top of the 100f (update: it gates now, filter scaling works, but no
cv-response yet..) my linn drum has decided to quit. I'm pretty sure it's
the batteries: first it was ok, then it wouldn't hold its patterns, and now
it won't even record a new pattern anymore.
inside are 3 normal rechargable penlights, but they're soldered to the
board. i've never seen it done like this, but then it's probably the oldest
'digital' machine i have. i assume these hold the patterns.
can i replace these with normal off-the-shelf rechargable penlights? or are
they a special kind?

thanks!

ruud