It's possible to source and replace faulty flash memory with new devices.

In fact I have them here with me, brand new original Fujitsu.

But a faulty memory device will mostly cause a system crash that is fatal and unrecoverable through a CD OS disc.

As your unit works, that's quite unlikely to be a Flash memory problem based on my experience. During it's normal operation the unit updates it's own flash memory with recent addressed and GPS locations. So if that update is occurring the memory must be readable and rewritable.