Help NEC NP-U250XG projector serial number format

[sls]

Help I want to extend the warrantee on some NEC NP-U250XG projectors that were installed during the summer when I wasn't here. I can't find the serial no on the case I guess it is under the mounting plate but I can get a serial no from the information screen on the setup menu. Unfortunately the NEC website doesn't like the format of this serial no. I guess it wants some leading zeros or sn or something that I haven't been able to guess. An example of the serial number I have is 128. Can any kind person tell me what I need to add to this to make it a valid serial no?

[sls]

Decided to take one down but as I was starting I found a paper label stuck on the back, now upside down and pointing at the white board without enough space to get my head to. Anyway just for completeness the format of the serial no is 2440xxxCJ where xxx is the serial no displayed in the setup menu. If I had carried on guessing it might have taken me some while to try that one.