IIS WCF 503 Errors - Where to Find Logs of Them

I am trying to figure out where I can find the logs which list HTTP 503 errors that IIS has been returning when servicing requests for a WCF service that it hosts.

I have looked in the following locations but I cannot find anything which indicates these 503s are being returned (I know they're being returned because the logs from our CDN indicate they are seeing 503s from the WCF service):

1. C:\inetpub\logs\LogFiles - There are no 503s in the relevant service's log files
2. C:\Windows\System32\Logfiles\HTTPERR - This folder doesn't exist (I only see SQM, Sum and WMI in the parent LogFiles directory)
3. C:\iislogs\www\HTTPERR - After some Googling, I found this directory could also hold errors however there is nothing in here related to the service and the logs don't contain any 503s
4. EventViewer - I couldn't find anything for the service in here other than some generic potentially dangerous path warnings

Where else can I look to find records of these 503s being returned by the WCF service hosted in IIS? Maybe there is a setting in IIS that needs to be tweaked?

You need to check your server configuration, hopefully there is no need for any change.

Powershell method

Import-Module -Name WebAdministration
Get-ChildItem IIS:\Sites
Get-ItemProperty -Path "IIS:\Sites\$SiteName" -Name logfileg

UI method

On the main page you have Logging which contains base settings

When selecting that you can see the setting details

You will see the same settings on each site, with some fields grayed out. To find actuall directory you need to get the site ID, Going into advanced settings does show the ID.