Solar Powered LED String Lights

Hi, I have a set of solar powered LED garden lights. There are roughly 240 LEDs in total, split into two branches from where the feed cable from the charger/battery box connects to the first LED. 

When powered-up, the first half dozen LEDs on each branch light up but get progressively dimmer the further along the chain they go until nothing at all. After that they are all dead except for one branch where the last half dozen on the string light up albeit rather dimly. 

Any ideas?