Small multi piece prints working - larger prints failing

[esoco]

You probable don’t need to replace the hotend, just unclog it. I had a similar problem after the first prints. For details see my answer to this post:

Spaghetti after perfect first layer

Is this your first print or have you printed successfully before? I had a similar problem - after several perfect prints print quality began to degrade with under-extrusion, first starting at higher layers and only with certain filaments, with some prints still successful, until all prints came out under-extruded. The problem was that filament residues hat accumulated in the hotend until it was almost fully clogged. Due to the force of the Bambu extruder it was still able to push some filaments…