I had 5 Golden Comets. I lost 2 within 2 months around 2 years old. One egg bound, the other was bleeding from vent. I put her down. Also at 2 years a hen retired from laying. I still have her. The other 2 still lay. One gives me 6/7 eggs a week. The other gave me 13 eggs this month, lays a week, takes a week off. They will be 38 months Wednesday.
I don't think I will get a Red sex-links again. May try a Black sex-links? They lay less than Red sex-links from what I've read.
I currently have 7 Barred Rocks, 9 months old, and I'm happy with them so far.
I would check on the things
@aart said, before drawing conclusions.
Spoiled feed dropped my Golden Comets egg production below 50%. Feed went bad at 5 months past mill date, had a strong medicine like smell.
When I washed the feeder and replaced with fresh feed egg production came back to average in less than a week. I caught it early. If it's been going on for a while, it may take longer.
I clean feeders and waterers regularly, more often in damp or humid conditions. It's also important to have plenty of fresh water available during waking time. Lack of water will impact egg production too.
I keep majority of feed in my house, heat and humidity will spoil feed quickly.
Also I experienced a drop in egg production when I gave them Scratch Grains twice daily as a treat. I cut back to once a day, except when it stays below freezing in winter, 2 Tablespoons per chicken per day, less for bantams.
I hope it's something fixable. GC