Multiport valve replacement

We have had problems with our multi-port valve for years. It is made by Americana. We have replaced the gasket which separates the two halves, numerous times. When we change valve settings from one to another the valve will end up leaking between the two settings, ie. backwash and filter to pool. I would like to just replace the multi-port valve unless someone has a suggestion. The valve is about 25 years old. We are having trouble matching it up. I was just. Going to search this forum for similar posts however I couldn't because I haven't made a post yet. Are the multi-port valve's made so that the plumbing will match up, is there a specially made PVC pipe ect. Any suggestions would be helpful my wife is threatening to pay someone to have it done so I've got to get going.
Thanks
Jojo