Hello,
On your older image of laptop, you would have to replace the Sylink.xml as well.
What version of SEP 12.1 are you running?
For SEP 12.1 clients older than SEP 12.1 RU2, you need SylinkReplacer for SEP 12.1 which is only available with Symantec Technical Support Team.
However, for SEP 12.1 RU2, you would need to use the Internal feature, check this Article:
Restoring client-server communications by using a client installation package
http://www.symantec.com/docs/HOWTO80762
SEP 12.1 RU2 and Reset Client Communication
https://www-secure.symantec.com/connect/articles/sep-121-ru2-and-reset-client-communication
For SylinkReplacer for SEP 12.1 utility, Create a case with with Symantec Technical Support Team.
How to create a new case in MySupport
http://www.symantec.com/docs/TECH58873
Phone numbers to contact Tech Support:-
Regional Support Telephone Numbers:
- United States: https://support.broadcom.com (407-357-7600 from outside the United States)
- Australia: 1300 365510 (+61 2 8220 7111 from outside Australia)
- United Kingdom: +44 (0) 870 606 6000
Additional contact numbers: http://www.symantec.com/business/support/contact_techsupp_static.jsp
Hope that helps!!