I need some help. I flushed out my trans and while it was a messy time consuming job it seemed to go alright. When I test drove the truck it was a little low on fluid because I flushed too much out. Anyway it was slipping in 4th so I put it in second and it seemed to work fine. I got some more fluid and filled it up but it is still slipping in 4th. In fact I don't think that I have forth gear at all but the rest seem to be working fine if I put it in third. It required quite a bit of a tug to get the pan out and a good solid push to put it back in. Do you think that I damaged something?
1. Does anyone know what I should be looking for when I open the trans up again?
2. If I undo the exhaust at the manifold will it let the exhaust drop enough to get the pan out without further damage? Does the heat shield on the passengers side of the trans need to be removed as well? Will the exhaust seal back up again when I tighten it back up or will I need new gaskets or something?

Thanks guys I could sure us some help.