I have a single puck system - not that old - was working fine and now it says "no gps". When the power is on if I disconnect and re-connect the gps come back and seems ok. However it won't work otherwise? I've heard the puk needs good voltage to power up - I've charged the battery and it seems ok - but I will try a new battery in the hope that works as the battery is 3yrs old. Any ideas before I go and buy a new battery?