Obviously, if you have reached out to your business customer and have gotten no response, there is a problem. Perhaps the customer's relationship manager could assist you in communicating with the customers to express the importance of updating your files with the information requested. If you are not the BSA Officer for your bank, perhaps s/he has additional information which should help you.
In the meantime, here are some places to start:
1) I'm going to assume you've got this covered
2) If the business doesn't respond, try going here to see if the business is registered: http://www.fincen.gov/financial_institutions/msb/msbstateselector.html
3) Because your location lists Texas, go here to determine what state or local licensing requirements might apply to the particular activities your customers are doing: http://www.dob.texas.gov/money-services-businesses.
Here's a page you'll likely find very helpful: http://www.dob.texas.gov/money-services-businesses/faqs
4) If your customer's activity is conducted as an agent for another, FinCEN registered company (such as Western Union), your customer will be able to provide evidence of agent status
5) Consult the FFIEC manual section for MSBs as a starting point so that you can analyze the customer, the customer's activity, and the customer's own customer base, and determine the level of risk.