Troubleshooting degraded quality in prints on a MK3s  

Troubleshooting degraded quality in prints on a MK3s

Hello. So I tried searching but it's hard to find something that matches what I'm seeing. If someone has a post that already describes this, please let me know the link or what keywords I should search for to find it, thanks.

My MK3s has been printing for years really great. Upgrade from Mk3 to Mk3s was also painless. I gotten many smooth and absolutely perfect prints from this little machine, it was always fire and forget, and I get a great print.

At first it made some ugly top surfaces, but I wasn't worried, lots of things I print are more structural, less visually appealing. Then it started to fail on that too.

This is the bottom of the print. You can see this already creates a horrible first layer, in patches. This is a 0.4 nozzle, 0.3 layer height and the print is a square with 54 mm sides.

The inconsistent base already is a bit problematic, specially for this print, I need a good solid bottom surface.

Next the sides are an absolute terror.

It's inconsistent as hell and I can pluck the layers appart with no effort whatsoever. There is near zero structural support here.

And to cap it off, top surface and supports.

As you can see the topsurface looks even worse. That rats nest shouldd have been a line of supports, you can see where they should have been on the zigzag lines on the left wall area about 2/3 from the front.

I've been checking screws and belts (not every single one, but pretty much every screw I could access from the outside, and nothing was loose). The filament in this print is new, but it happened on older filament as well (all PETG, all the same vendor+brand) and I have many great prints from the previous spool. I cleaned the nozzle and heater block area with a brass brush to make sure nothing comes into the print and prohibits clean printing.

Any ideas where this comes from and how I can restore my printer to it's old goodness?