Layers adhesion after MK3 -> MK3S upgrade  

Layers adhesion after MK3 -> MK3S upgrade

Hey folks, how are you? I'm having some troubles with prints after MK3->MK3S upgrade, maybe someone could point me in the right direction?

So, the long story short, I had grabbed my trusty MK3 when they just came out, and I was very happy with it ever since. We had printed a lot together. And because it was such an awesome dependable tool I decided to cave in an upgrade to MK3S a few weeks back.

* I printed all the parts in PETG
* Ordered the missing bits kit from prusa directly
* Pulled the thing apart got it back together fine
* Upgraded the firmware to MK3S
* Got the latest PrusaSlicer
* Swapped the printing profile from MK3 -> MK3S
* Run all the recalibration from scratch
* Run the first layer calibration the usual
* Printed the benchy

So, it works perfectly fine, the prints look as good as ever (i have the IKEA enclosure thing for stable printing conditions). the only thing that bothers me is that there is seems to be a weird issue with layers adhesion. Here is how it looks like

I used to print a fair bit of PETG, cups, bowls, etc. and it always was watertight on MK3. After an upgrade I had printed a water bowl and it leaks water. It doesnt drip, but i can clearly see water getting between the layers, and eventually leak out and assemble into a small pool at the end of the day.

I also print a fair bit of ABS, mechanical stuff. After the upgrade I printed some M12 bolts. eSun ABS+, Vertical print, 3 layer walls, 25% infill, and they snap when I try to get them through a tap to clean them up a bit. That never happened on the old setup, it used to take a fair bit of try to snap those along the layers, now they feel fairly brittle and break easily.

At first I thought, maybe the new cooling system is playing tricks on me, or maybe the old termistor doesn't work properly anymore or something, so I had tried to bump the print temperature by 10C (255 -> 265). And it didn't do much, the pieces are still rather brittle along the layers.

I feel like there is something funky going on, maybe some tiny bit of underextrusion or something. Which is a bit out of my depth to troubleshoot. So, I would appreciate a caring hand and some wisdoms. Thanks!