Recently acquired an 7790 diesel with power steering. Hobbs meter shows 497 hrs. It does not run. First issue I find is the fuel lift pump is not working. The umbrella check valves are ruined, possibly by incorrect fuel additive. I need 2 of these valves. 3/4" dia. with 1/10" stem. Holly carburetors and Harley motor cycles use a similar, but different size part. Have some doubts as to diesel fuel compatible. Have ordered a small electric fuel pump due for delivery in a few days to help me work through the remainder of the fuel system. Intended to get the engine running but only as a temporary fix. (lol) Does any one know of a good source? Any help appreciated.