I have a C-5700 Shimano 10 speed cassette with probably 3k miles on it. The chain is really noisy on cog 14 & 19 like it needs to shift. I have messed with the barrel adjuster but it doesn't solve the problem. I'm wondering if those cogs are worn. I can't see any difference but haven't taken the cassette apart. Can you buy replacement cogs for a cassette these days? Thanks for any feedback.

first off, i would check that the cassette AND lockring are on tight.

If you have 3k miles on that cassette, it's entirely possible that at least those 2 gears are worn (possibly others & the chain)
They may need to be replaced.

Cogs are not worn at that mileage. I would pull cassette, clean drive train, install new cables and housing. Retune and lube I bet it goes away. Cable and housing cheap in bulk and the rear loop goes bad first.

I just switched out a 15 that was noisey ( had a couple cass wasn't using) also miked the spacers and replaced both sides with other I found to be .01 thicker . I'm thinking your 19 is in a group of 3or 4 . Did small search for seperate cogs didn't find any 14/19 . Harris Cyclery (Sheldon 's place did once sell single cogs)

good luck

Most people wear cassettes unevenly by spending different amounts of time and load on various sprockets. Meanwhile the chain is wearing also. So very often the chain will be noisiest not on the sprockets that are used the most, but on the ones used the least.

The pattern can reverse when a new chain is installed. The new chain will run better on the newer sprockets and worse on the more worn ones.

Before we can commont on the specifics of your problem, we'd need to know which sprockets you use the most, and also which one see the hardest use. For example, I spend the most time riding the 2-4th sprockets (from high) but the 5th gets rough use, because it's the one I tend to use when sprinting some of the short steep hills I climb when I'd rather not downshift.

The chain has probably 500 miles at most. I'm guessing that those two cogs are the ones I use the most. I think the 19 and 21 get the hardest use because I use them the most when on the hills. I haven't called any shops looking for individual cogs yet but couldn't find any sources just looking on line.

Individual sprockets are hard to come by, and if you find them, so expensive that 2 would cost about what a cassette does.

I'd live with the noise or (shameless plug coming) use a chain oil that effectively muffles the noise.

That sounds like good advice. Also I think the shop had some Chain-L the last time I was in there. I might just try it out. Thanks all for the info.

If the bike was serviced by a Chain-L dealer, he might have intentionally made those sprockets noisy so you'd come back and he could sell you some Chain-L.

Ok I'll tell him I'm on to him and that is straight from the Boss