Somewhat new to 3D printing (about a year), but started with Creality and have several of their printers as well as a second HI Combo. Never had an issue with initial setup until this unit. I received a new HI Combo direct from Creality. Assembled and ran through the calibration / update / calibration process as usual. Upon starting the first print, the purge line dug the nozzle into the PEI sheet. Ran another calibration. Same result, leaving a big gouge and shredded PEI bits behind. I double checked the nozzle install, then checked z-offset manually through fluidd using a feeler gauge. Everything appears to be normal. But in order to make a print work, I have to set the z-offset to +0.300, and even with this, the purge line still drags the nozzle against the plate, causing the extruder to skip a few times until it gets to the front left corner and makes the turn. At that point, filament will start flowing and the print will usually turn out OK. I am working with Creality support to troubleshoot, but with the time difference, updates are slow going. I was hoping someone here could help me out with ideas. I have a new strain gauge on the way, just to see if that makes a difference.
My printer has been scratching the build plate out of no where, it would work perfect one day the next it would start scratching the build plate for no reason. It has ruined two plates already.
To fix this, I reset to default settings and reinstall creality print. When the printer is in ‘scratching mode’ I have tested it by sending a print from orca slicer and it does not do it, leading me to think it could be a creality print issue as well.
Did you get this sorted. I was having lots of problems with Z offset recently but after a creality print update a while ago everything came good. I think the Hi is a bit of a work in progress 
Somewhat. I landed on a Z-offset of +.250, and this seems to have fixed most of the issue. However, when it does the initial prime line, the first half is still so close that no filament will be extruded.
Have you updated to the latest firmware and software (Creality print) I also did a full system restore so Z offset back to 0.00
Working fine now. Also replaced nozzle and found original nozzle was loose…finger tight.