Chain twitch during drive on new RowErg

[CRO_Express]

So, question. Model here is Rowerg, produced end 21, with currently 170k meters, so almost brand new.
Chain and flywheel bearing has been slightly lubed, did not make any changes.
What is happening, during the drive phase I notice visible twitch in the chain which you can feel through handle, around half way through the drive, it's like it moves ever so slightly to the side, realining itself, does not slip. This happens around 2:00/500m and faster, does not happen every stroke, happens in around 20% of them but in same location. Interesting enough, ususally does not happen in first 1000m rowed, perhaps sine i row slower here.
When you fully pull the chain on erg, you see that it's not 100% straight, but you can correct this by moving links with hand.
I've inspected chain for stiff links, could not find any. It's almost like the brass handle is not correctly in place and then sits back half way in drive.
How long does it take for erg to fully 'break in'? I've also considered dirt in sprocket, but I really would like to avid this extent of dissasasemly on new machine.

[p_b82]

My erg - bought last year had zero bedding in time; so what you're experiencing sounds like some form of defect.

I'd contact c2 directly to get them to assist with further troubleshooting - in tandem with anything any-one here could suggest to look at.

[Carl Watts]

Its possible that the chain can actually get bent.

I suspect a new chain will fix the problem. As long as the swivel on the handle is moving freely and where the chain connects to the steel has a bush inside so it can rotate freely and is not jamming, then its the chain itself.

Have you oiled the chain, those links need to move really freely, they move under their own weight there should be no resistance at all. Stiff or totally frozen links are quite common.

[Ombrax]

If you suspect the "jump" is coming from there, you could try putting a teeny bit of chain lube on the steel chain swivel fitting / brass bushing / U-bolt interfaces at the handle. The high contact loads will quickly displace the oil, but if it works for a while it will confirm that the issue is located there, and not due to the chain proper.

Good Luck

[CRO_Express]

viewtopic.php?t=185726
I've used the thread above as an inspiration, gudilines by Ergmesiter.
I inspected the sprocket, looks brand new, which it is Plastic band is orange on mine so it's clearly visible.
I have also inspected the chain for stiff links but each link performs on the pen test exactly the same as the ones before it, no difference, all bend very smoothly.
I'll post a pic of the chain in the morning, to see the slight curve it has cca in the middle, but I recokon this cannot be the culprit, since you can move all these links by hand into other angle.

[Carl Watts]

If there is a curve in the chain, its stuffed.

[CRO_Express]

If there is a curve in the chain, its stuffed.

What do you mean by stuffed?
https://postimg.cc/gallery/s1GpwTD

Not sure if pcitures help, there is curve near the handle, but this part does not go onto sprocket.

[CRO_Express]

Just to update the case. Problem is still there, same as before. I've tried returning it to Decathlon, describing the issue, low rate, high power stroke. The log says they tried it two time, two minutes times, rate 27, 2:30 for the love of god Of course, they did not find any issues with it. C2 Germany could not help much either, asking for video of the problem which I cannot provide, handle has to be felt.
Bottom line, I'll either buy new chain and replace or sell it on.

[GreenStratMan]

I get a click through my handle. It is definitely coming from the swivel. You may find you can replicate it at slower speeds if you roll your wrists back slightly at the end of the pull. My chain is recent and from new there were very slight left to right variances. I think that’s normal, within tolerance.