Copyright 2019 Nicholas Kalis
Published photos of my Fn3 layout in Narrow Gauge Downunder revealed that a diagonal was missing from one of my gates. I installed the missing weathered diagonal in September 2019 (as it appears in this photograph).
Lesson - Photographs can catch mistakes that the naked eye often misses - the fault does not all lie with our eyes - our heart tells us the model is perfect when our head should tell us to be a bit more critical. Even our friends might not catch an error.