So, i have not forgotten this thread. Really :p
I have now printed quite a bit, both PLA and PETG, and just now received a small roll of TPU, which i want to experiment with.
A lot of things where mentioned in this thread, that by now i had the opportunity to learn myself :p
One thing i found especially interesting, i do not know why that happens. The printhead of the Prusa seems to draw crud like a magnet. It's already really dirty, with barely more than 55 hours of printing. Sometimes, when extruding after filament change, the extrusion curls up so much that the end sticks to the nozzle and a loop is formed. That drops off, but always leaves some residue. One time this happened when printing though, and i got a big blob of PLA stuck to the printhead.
I especially had issues printing white PETG after PLA of other colors. Many prints got small ugly pieces of crud in them. I assume that these are remnants of PLA stuck to the head that dropped off on the higher PETG temperatures. I think a silicion sock, as was mentioned here, might be a good investment, at least it would make cleaning easier.
But in general, how does one go ahead to clean the printhead? I got a brass wirebrush, but everything around the actual printhead is plastic, and the heaterblock is recessed, so i dont think i can really go ham on the head with the brush...
Also i noticed, after using the brush, sometimes the filament extrudes wierd. It comes out wider than the nozzle, as if it puffs up. But actual prints still work fine so far.
I printed quite a bit of PETG, and that sticks really nice to the textured sheet, i had barely any issues. After switching back to PLA though, i had massivie issues getting that to stick again, even though it worked fine at first, with the same settings.
The solution to that? Giving the bed a thorough clean with soap and washcloth.
I will still order a smooth sheet at some point for PLA. The adhesion is just too borderline on the textured sheet.
No pictures at the moment, i will post some this evening though, with a description of an additional problem i am facing at the moment.