In my attic I have a Ruud Silouette II, UGPH-05EAUER, Plus an E-Z-AIRE air to air Series 70. In the Series 70 unit I found a rigid metal framed filter 13 1/8” X 17 ½” about 1/2 " thick. Foam deteriorated. For now I trimmed down a cardboard filter but would love to find the original replacement. Short of a custom built expensive one anybody know how to order an original replacement??