[Ten Hammers]

For the sake of arguement I assume the new gun ( lead ) came with a new liner but don't know. As noted starting at the wire end, check the feed tubes and rollers for clean and alignment. If old liner you can remove it and clean it with brake parts cleaner or soak it in carb cleaner and replace it with new one. Then have a clean liner to exchange. Clean ( good quality ) wire is a must. Many folks here have years more experience than I. THese things I have listed may solve your problem. A Nice cheap little clip on felt wiper with some magic juice that they sell in a can may keep the nasties from entering the first tube and then on down the line. good luck. The liner may or may not have a booger on EITHER end as it enters the lead ( or gun end ). Think of this as a cable housing and you want free passage of the wire through the liner ( housing) with no bind.