Entry slug auto appends -1 even when the original slug is unique
I don't know the specific rules Craft uses but I believe Craft auto appends the -1 when it tries to save an Element that has a matching URI in the craft_elements_i18n table.

A few scenarios that I can think of that may behave like you describe:


Somehow, there is an existing record in your database that matches the URI of your Entry using the cics-west-belden slug
You have another Section, Category Group, or other custom Element set to generate URIs in the same format as the Section you are posting the Entry to which already has an Element saved using your cics-west-belden slug.


To rule out the scenario where a matching record already exists in your database, open your database and look in the craft_elements_i18n table. Search for all records that match your slug and see if you only find the one:

SELECT *
FROM craft_elements_i18n
WHERE slug = 'cics-west-belden';


To confirm that no other URIs already match your Entry, you could do a similar search in the URI table:

SELECT *
FROM craft_elements_i18n
WHERE uri LIKE '%cics-west-belden%';