Drive chain noise

[bsw]

My drive chain is making more noise than it should... it's a grabby, slappy sound under gentle acceleration. It's probably noisy when accelerating hard as well, but I can't hear it. It's nice and quiet when just coasting along or engine braking.

I came here last week looking for help and found threads suggesting the front sprocket nut could be loose - and it was! So I tightened it and things were quieter for about 100km and then the noise came back. Figured it had come loose again so went to grease it (so I could get it really tight) and re-tighten it. But, it's still tight.

I know my chain is a bit worn, and strangely worn - there are tight and loose spots as I turn the wheel. Both sprockets seem to be rotating smoothly (no bent countershaft) so I assume it's the chain.

I've also double checked the rear wheel alignment several times.

I suspect I just need a new chain - but checking in here in case anyone has any other suggestions for things I should check.