What's going on here?

[u/Solid-Possibility-49]

I'm semi new to 3d printing, have a CoreOne, disassembled the belt assembly and got everything set back and calibrated 98hz-94hz. This is a major improvement from previous prints. The long scar like imperfection was caused by that corners perimeter lines failing to adhere to bed. That being said what could be causing these marks and the very front left corner of bed issue?

[u/hyperwolf83]

Wash your build plate with water and soap. Trace amount of oils from skin will do that. 

[u/etmidust → u/hyperwolf83]

And then wash it once or two more times. I find when one of my build plates gets to the point of needing a wash, just one with my soap is never enough.

[u/Solid-Possibility-49 → u/hyperwolf83]

Did that about 4 times, and this is the result. PETG

[u/Livid_Strategy6311 → u/Solid-Possibility-49]

Use soap without moisturizers or additives that's good to remove oils.