N14 Top End Knock

Hey everyone,
Trucks been OTR for about three days now and my drivers telling me there's a top-end knock on cylinders 1-2, he can't really figure out which it is. I had him use his phone as a stethoscope to narrow down where it was but I get an error when I try uploading that file here, its an audio file and that seems to be not allowed. In essence, sounds like someone is tapping the head with a small hammer on the passenger side of the engine, its normal noise down by the rocker boxes and cam. The number one cylinder had its injector replaced not two weeks ago from a truck that was running well and that fixed smokiness on startup. As per the old thread, there was a hefty amount of algae in the tanks that was not discovered until after the truck had stalled several times from the filter getting clogged up, I'm wondering if that could have damaged the injectors or allowed some of the algae to get through the filter and clog the injector mesh filter. I'm not sure if this is a bad overhead or a dead injector, the driver says it's not down on power at all, but the knocking has him concerned.

 

It started off like that, you could throttle it up and it would disappear but now it knocks continuously, it quiets down with throttle but doesn't disappear like it used to.

 

That's what I was thinking, I read on here a while back that Cummins stopped making these injectors and the quality of remans was really lacking, does that have any merit or just some hearsay?