At the end of my sanity; hopefully someone has the golden tip

First some background. I have a vCore 3 that was upgraded with the vCore 3.1 kit and later the RR Toolhead and a beacon. The printer has printed well for the longest of times untill I had a massive clog on the old EVA toolhead that broke my Pheatus Rapido. I decided to "splurge" and get the new toolhead, complete with a new hotend, extruder and the beacon probe. This is where the issues began for me. For the life of me, I cannot get a consistent first layer. I let the beacon do it's thing, make sure the nozzle is clean, and use a piece of paper to check if the Z=0 is actually spot on - which it is. When I start the print the maddness ensues. It seems that the nozzle is either too close, after which I raise the head with microsteps and complete the print. I use "save Z-Offset" in the new RC 2.1 firmware and save_config; the next print it does it again. Some other small facts / questions: - The frame is square (get about 0,138mm height difference). - I do have a small offset when I do multiple heightmaps, but in Z. The "min-Z" seems to move around 0.004mm up when the system heats up - Is there supposed to be some play on the toolhead or is it meant to be completely rigid? It is driving me bonkers; hope that someone can point me in the right direction.