Did the calls that used to work indeed work with the same Fortran library binary -- or has the library bee recompiled/updated? Because I see that the Fortran compiler g77 has
-fno-underscoring which must be set to prevent them. Recompilation without that option (which was present for the old libraries) would explain that you cannot link anymore code which you used to. If that is so, you can perhaps convince the distributor to produce a compatible library. Conceivably, you have one that is meant to be linked against regular Fortran programs!