Not sure how to crack this

Hi all.

We have a CNC at work that gets itself into a pickle at times.
We need to access service menus which require a OTP. The MFG has no problem generating/giving us the OTP, but we run 24/7 and the MFG doesn't So in theory we can lose 7 shifts worth of production (if it happens after hours Friday.)

The way it works is, the CNC (Windows XP based application) will generate a key, we give the MFG that key, they return us the password/key.
They keys look like a Windows activation. 5 groups of 4 AlphaNumeric characters for both the key and password. Not case sensitive.

I've saved some of the old combos. Sometimes they would work for the entire day. And on a couple of occasions been able to turn the system clock back and use older combos. But not always. So I think its date related. Maybe hashed against it or salted with.

I know I'm probably not giving enough info, but ideas? Thoughts? What other data might be needed?


(Having worked for that MFG, I doubt they did anything super fancy, but they do have a complex)

TIA.