I have a 4 year-old Smiths Timeguard ZV700 switch, whose timer mechanism
has ceased to function: the lcd display is blank. I suspect the internal
battery is dead. Smiths helpline is most unhelpful: no user-servicable
parts and we don't do repairs. Does anyone know (a) how plausible my
suspicion is and (b) what the internal rechargeable battery is likely to
be? It has "061" printed on a green sleeve; nothing I can see on the
battery itself.

Thanks,
Douglas de Lacey