Hi, we have an old Hayward GM-245 Sand Filter with a SP-711-20 Multi-port Valve. The return line was leaking last year and it appeared to be dripping from the valve assembly and not the hose or coupling. As it is very old (1981?) I was looking for a replacement. All I could seem to find were replacements for other 711 series valves (SP-711-13 etc.). Would anyone know if we can use the replacement valve for the SP-711-13 for this one? Thanks for any guidance!