[traceroute66]

> If the other end is plugged into a transceiver, don't look at the fiber end directly

Let me fix that for you.

Don't look at the fiber end directly, always assume it is plugged in unless you can see the other end yourself with your own eyes.

Fibre light meters can be bought cheaply for a basic troubleshooting bag kit-out if you don't fancy splashing out on a fancy device.