[Lazybones]

I have a 1998 Express, with 3208 CATs. Has anyone seen an air leak in the fuel tank selector valve. I did a filter change and am now drawing air into the filter from upstream, but only when set to draw from the port tank, belly tank ok. All hoses and connections are tight. Had no problems prior to the filter change, but the selector was very hard to turn when shutting off fuel just prior to the filter change. That is why I suspect the valve. Also the valve stem has about 3/16" play in and out, which seems unusual. They appear to be Groco 6 port valves. Valve is hard to get to. Can they be rebuilt or just replaced?

Any help appreciated.