none for an
ITG S2000 but there are some manuals for the IGT S2000.

The download area here on NLG has several documents, manuals and info sheets for the S2000. Below is a sample screenshot of some of the files. But to access the download you would need to make a contribution (large or small) to the NLG website to help support the cost of keeping it running. Most people say the help that is available from the experts here, plus access to the download area, is well worth a donation.
For tasks like making a volume adjustment you can just post a question asking how it is done and someone will walk you thru it. No charge for the free advice.

Also, a google search may find a pdf manual somewhere on the internet that contains what you are looking for.