P802QR2 : drops of PLA disturbing printing and not sticking

Hi,
I've been struggling with my new Zonestar P802QR2 printer: after some unclarities (solved in other topic) for testing levelling, I now face printing issues.

I tried the test gcode file (R2_Test_Block.gcode) provided by Zonestar to test offset of extruders and I can't make proper printing, even with only the 1st extruder.
For instance:
- at very beginning, the PLA filament drops a bit from extruder and when moving to the heatbed, it creates thick "lines" which don't stick very well and which are later "touched" and "pulled" by the extruders (which unstick the whole model and screws up everything)
- the PLA (the one provided with the printer) does not stick well on the heatbed (covered with the blue tape provided also by supplier)
- when the 2d extruder starts, I saw it's even worse..
I rechecked the levelling and I think I do it right: I can slip easily one sheet of paper underneath, but not 2 sheets. I saw in some forums that the sheet of paper should "hardly" pass underneath, so maybe I'll try shorten again the space.
The heatbed does not seem to be very hot (LCD states 50°, but I'm not sure it's that hot: a meter tells me 40° on the blue tape): should it be hotter or colder (I had read on some forums that blue tape should not be heated at all ?). (The plate doesn't stick perfectly to the heatbed heater, so I tried to add some thermal paste in between, but I've not seen much improvement)
I uploaded a video of such print : https://youtu.be/PSjgqjMVZM4 Can you have a look and tell me your opinion ?

I also noticed that the 2d extruder is slightly higher than the 1 extruder, but I couldn't find document on how I can adjust its height and align it on 1st extruder. I looked at the doc "how to assemble hot head" from Zonestar, but it's not clear how to adjust height. Anyone would have an idea ? I found a couple videos on youtube, but it's not the same printer so I still don't know to do it.

I tried printing also through Cura in case it's linked to the gcode file. But issue seems about the same. Look at this video: https://youtu.be/OW8aVlW1MO8

As I'm new to 3D printing, I feel lost, not understanding which bigest issue I should work on first.. temperature, levelling or anything else.. If you can help me..
br,

Ricorico94

You need to adjust the nozle height a lil bit lower to the bed.I find it about right when i can just pull the paper

Hi,
I tried to make it closer, and it seems having improved, thanks. Not perfect yet, though: could it be also due to temperature of the heatbed ? It's a metal plate covered with blue tape.. Should it be cold, at 40° (as it seems being the case so far, though machine states 50°), or even warmer ?

br,
Ricorico94

I use mk3 alluminium bed coated in blue tape, the best temp i have found for medium size prints is 55-60
In your slicer setting's set the initial layer height to 0.25 or 0.3 and set the 1st layer extrusion width to 200%
I allso print the 1st layer (pla) at 200 then drop to 195 for the rest, helps it stick to the bed better (slic3r has tis setting, not sure if cura has tho).