K8200 prints some projects perfect, but not others

Hey guys, new to the forum and the 3d printing game!
I’m having some issue when printing some projects.
Some projects seem to print perfectly, like this one

thingiverse.com/thing:807945

But then other projects don’t print properly, like this one

thingiverse.com/thing:234451

When it has its issue, it seems the extruder is too far away from the print bed.
Could this be a problem with Slic3r and the way it determines its GCode? Would another slicing program work better?

Thanks!

Could you post a picture of the failed print?

The print that is failing could be a little tricky.
I tried to load it and saw that it was not sitting on the bed in the software.
You may need to flip it over.

The K8200 does not use a buildtak sheet but your bed does need to be clean.
I use alcohol to clean mine before every print.
I have found that the more you clean it the better it sticks over time.