10-10-21, 09:24 AM
As far as I'm aware no chain tensioner starts at the beginning/No1 of it's range they all start in the middle ish. All tolerances on chains and sprockets, gears cams etc vary, which means any given new cam chain could have 5mm or so more free play than another. But they should wear at the same rate, i.e. chain A starts at position 6 chain B at 7, the service tolerance is say 15mm each tooth is takes up say 5mm. To reach max service life chain B is on 10 out of 12. What often happens is the wear just isn't enough to get over the tensioner tooth high point by just the spring tension alone, it needs a little help. By revving the engine into it's higher rev range it stresses the chain just enough to allow the tension spring to overcome the chain pressure to get over the tooth high point and then settle back engaged the next tooth, but taken up that extra 0.5 mm or so. 
I'd be amazed based on that video if your chain is shot, just rev it
I'd be amazed based on that video if your chain is shot, just rev it
Later