..and I wouldn't change any glow plugs or even try to loosen them, just spray some PB Blaster, etc. at the threads while you have access. Couldn't hurt. Really only two gaskets involved - the intake manifold gasket and the square gasket with a bolt in each corner that goes between the intake manifold and the EGR housing. Both are rubber coated metal and should be replaced - as all gaskets should but of course gaskets are often re-used with success. I really don't think you'll accomplish anything by just trying to look. It'll be black and gunked up inside even if the EGR is working. Don't spray into the vacuum tube or its connection. That will just put whatever you spray all over the rubber diaphragm. No access to the moving shaft of the egr valve itself from that side. Review the links that whunter posted to be sure you've exhausted all other options first.