HajduR

Dear All, I recently bought a used Ender 3. Since then I changed a thermo sensor (thermal runaway) , the bed (from glass to magnetic), the nozzle (0.4), leveled the bed - probably badly, tightened a pully and the x axis was loose a bit - I fixed that with the eccentric bolt that holds the lower bearing. So I am new, learning as I go. I am not satisfied with the print quality and I think the problem lies in me. My inability to set up the machine right. Please take a look at this picture. I think this is the first layer. Big gaps on the print. The plastic is sticking to the bed as you wouldn't believe, it is really difficult to get it off. I am using the filament I bought with the machine, maybe it is bad quality and I have to change that... I don't know. Can you help me troubleshoot? What should I do to improve print quality? Thank you Best regards, Robert