Peter Clark writes:

My GPS had been working perfectly (albeit with a year-old database and
much older firmware) until last month. (How old's the firmware? I'm warned
about ARSA's!)

Do these units have an internal CMOS battery which might be dead?

DING!

Reviewing the fantastic manual, (Yes, F is for Fantastic) I find that
there is indeed a statement saying that the NMC memory is maintained by a
lithium battery with a 5-10 year lifetime. It's not a user-replacable
item.

So - I'm off to the shop, with not just a symptom, but also a pointer to a
solution. That definitely could be the solution.

Thanks for your help, Peter!

-Jack