Cambridge Model 10/20/25 and 302/302A recorders contain Garmin
Receivers used for GPS reception. These receivers use internal (a
metal shielding cover needs to be unsoldered for access) 3v
rechargeable batteries. This battery keeps a memory chip "alive" when
the recorder is turned off. Most of these receiver batteries are
starting to or already have reached end of life (unable to hold a
charge) due to their age. These Garmin internal batteries have nothing
at all to do with the 3v security batteries that need to be replaced
every few years.

One of the side effects of failing batteries are what y'all have been
describing. Basically the Garmin has lost it's memory and defaults to
its original settings. Since the last date, time and location are lost
when the device is turned off, it can take awhile, sometimes a very
long while depending on which version of the Garmin Receiver is
installed in the product, before it determines where it is and
subsequently locks onto enough satellites to get a 3D fix and update
it's memory. Depending on the state of the battery the stored data may
be lost as soon as it's turned off or however long the battery can
keep the memory refreshed.....an hour, day, week.......it will vary
and get worse.

Sometimes, not often and I'm not sure why, the Garmin receivers will
get a fix but not update the date correctly. At that sorry point they
will need to be serviced by a qualified service tech. The rechargeable
battery can be replaced with a new one and the Garmin can be
reconfigured.

ST