Lost Name - Change Gazette copy (Mumbai)?

Got married 25 years ago, had to change the name as well as surname after marriage. Had got appropriate name change gazette issued then.Was working as a lecturer in the same institute before and after marriage .However i seem to have lost the copy as of now, the pension department now insists that i get the gazette copy to prove that i'm the same person as per the two names mentioned over the service book. The marriage certificate copy just shows the change in surname and not the First name.Any solutions to this tangle?