Issues with printing , layers not adhering

Ender-3 V3 Printers
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Hi everyone. My mum gave my daughter’s got ender pro 2 3d printers for Xmas - one each. One prints totally fine , I’ve managed to learn to configure it, level etc and it’s really good. The other one is having issues I cannot figure out. It prints small simple pieces ok. Anything taller than about 2 cm though and I get stringing and layers not adhering. I have attached photos to show you. The first couple of layers look great and then it goes wrong.

This photo is from the top. You can see big lines between the layers and also between the filament.

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I’ve tried playing about with the heat of the nozzle and the bed. Levelling and RE levelling! I’m fairly sure I’m getting that right though as it’s working for smaller pieces and for my other daughters printer. The filament is Amazon basics but is working ok on my other daughters printer.

Thanks in advance for any help!!!

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This photo is from the side

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This photo is from the bottom. You can see the first couple of layers look ok, I think

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  1. with the printer turned off.
  2. does the print head move up and down, if so the plastic pulleys need adjustment.
  3. check also the Z up down movement, is there any slack .
    also check the Z leadscrew is tight in the metal housing.
    its probably something loose.
    can you use menu to drive Z up 150mm and see if its smooth running