ADTech is on the right track...
Are we trying to solve a real problem that every viewer sees? If so, how do they describe the symptom(s). And, we need to know what your antenna has to work with. Everything downstream of the antenna depends on what is available in the air.
As ADTech suggests, please post a TVF report.
http://forum.tvfool.com/showthread.php?t=4
Or, are you like me, inclined to look for trouble no one else would notice? Sometimes I break things while trying to 'fix' them.