Maple uses Octal code 261 for the minus sign, a "-" sign in the Adobe Standard but a "+/-" sign in the ISO Latin 1 encoding.  EPS viewers (i.e. Ghostview) may use ISO Latin 1.  You can, if you wish, edit the .eps file with a standard text editor (i.e. replace instances of Octal code 261 with a "-").

Below is a Maple procedure which will do this automatically.  Feed the procedure the full path of the .eps file in quotation marks and it will produce a new file with a ".new" extension.

fixps:= proc(filename::string)
# filename is the name (with path if necessary) of the input file
# optional second argument is name of output file, otherwise ".new"
# is appended to the filename
local S, file2;
if nargs = 1 then file2:= cat(filename,".new")
else file2:= args[2]
fi;
if file2 = filename then error "File names must be different" fi;
S:= readbytes(filename,infinity,TEXT);
writebytes(file2,StringTools[SubstituteAll](S,"\\261","-"));
fclose(file2);
end;