TMG 2010- SSL web access via port 2096

I configured TMG 2010 some time ago with additional SSL ports so that our internal users can access an externally hosted https website on port 2096. It worked fine for almost a year, until today...
Here is the TMG configuration:

C:\Users\marcos\Desktop>cscript "show added ports.vbs"
Microsoft (R) Windows Script Host Version 5.8
Copyright (C) Microsoft Corporation. All rights reserved.

NNTP: 563-563
SSL: 443-443
SSL 2083: 2083-2083
SSL 2096: 2096-2096

I could try to recreate the added ports but I'm reluctant to do that because it may require a restart (downtime) and probably won't solve the issue.

Many thanks for your help!

---

Marco S