I have a meridian xl programme date 1996 I bought it new about 14 years ago it has suddenly stopped locating satellites .i suspect it may be something to do with the internal lithium battery which has never been changed the manual is of no help other than saying it does contain a battery. Does anyone know the purpose of the battery and is it user changeable?...Incidenlly the unit still retains waypoint information. I can't see the lithium battery lasting that long unless somehow it is kept alive by the main batteries.