[Electronic M]

Correct me if I'm wrong, but didn't the OP figure out that the smearing is there if he injects video at the first video amp and gone if he injects it at the second video amp?
If that's the case he should fix it so that he can get smear free video when injecting at the output of the video detector before worrying about the front end and IF sections.
I'm not saying the front end doesn't have issues, but if there's issues in the video stages too then they will hide any progress or other issues in the front end and IF stages.

When you have multiple problems in a TV there's often an optimal and a counter-productive order to tackle them in.