hello, i was wondering if any one can help me get a pressure reducing valve for a double siphonic toilet. i know that you can't buy them any more. i was changing the cistern contents and hadn't come across one of these toilets before i threw the old siphon away and didn't think anything of it until it started blocking up and didn't flush properly. i don't want to change the toilet as it's really nice(as nice as a toilet can be).i hope someone can help me.