Why are some of my string of LED lights dimmer than the rest?
With the help from Peter Duniho I tried reversing the strands and found that the problem persisted. My dad then suggested I put the defective strand in the boiler room to dry it out in case water had gotten in the circuit.
I left the strand for 30 hours and tried it again and it worked!
When I hung the chain again I could see water in two of the bulbs.
Many thanks to the people that provided helpful suggestions!