homefinder

Hi- I have a Magellan 1400 and its about 2 years old. It has worked great until maybe a month ago and the problem begin intermittently and now has progressed to not working at all. When using the unit the screen would just go black or from time to time and it would ask if I wanted to continue on battery power. My car power cord has an indicator light showing that I have power so I would move the cord around and the unit would come back on so I thought maybe the cord is bad. Bought another cord, same problem. I am about ready to buy a new battery but I don't want to put too much money in this unit, I may just be in the market for a new GPS and maybe another brand. Does anyone have any suggestions as to what my problem could be before I either put more money in this one or buy a new unit ? Thanks for any suggestions you may have.