I have two TomTom 5000s. One has been unused for ages, other in regular use. I've been having problems with the current unit, although working perfectly, in that it started to cycle on and off, saying power disconnected shutting down. It could happen several times in one minute. Much tweaking of cable later, no help. The sheer number of on/off messages made me wonder if it was more than a bad contact. Have replaced cable with no improvement. Using windscreen unit 4UUB etc. old unit is no better, though both will run normally from my computer. I've tried cleaning base unit contacts with no result. Is this unit just a set of contacts, or are there potentially some electronics within which may be faulty? Can't find a replacement on the net, would a similar looking '9' prefix unit work?? Any help would be appreciated.