Before attempting DIY maintenance, ensure proper safety precautions to prevent electrical shocks
Interconnecting fairy light strings are not working
There is a small key in the extendable adaptor to ensure proper alignment ie. ensure the lights are correctly plugged into each other.
Some strands are not lighting up
It means that one wire has probably pulled out (disconnected) in the dead section.
Look for a loose wire, or a discoloured globe.
Replace the wire into the sleeve (and use super-glue), or remove the bulb completely and connect the wires to allow the current to continue to flow.
Rope lights not powered
Some sections eg 3 LEDs or 1m do not work. Considere cutting out the entire 1m section by cutting at the scissor marks only, and use a connector to re-connect in the correct sequence.
If the entire length is dead using a new power cable, try connecting the power from the other end (some power cables are wired inverted).
Look carefully at the rope light end. There are 2x offset wires. Similarly, the power cord has 2x offset pins
Ensure the pins insert into the wires. Take precautions if the power is still ON while doing this.
You may have to remove and then reapply the shrink sleeve with silicone or some other tape sealant to avoid moisture getting into the connection