Since then support have asked that I check the wiring continuity between the Rambo and the print bed. After an initial false positive I’m now reasonably certain the wiring is ok.
I’m now waiting for a follow up response from the support team. I’ll post any more information here when I learn anything.
30-JUN: Support have asked me to test the printer using Cura to see if the temp fluctuations occur. I’ve only used Octoprint to drive the printer since the initial print so it will take some time to setup and run that test,
Thanks for documenting your troubleshooting progress here, Daniel - hopefully it helps anybody else who might encounter this behaviour to get in front of it even quicker.
I went back and did it again using thicker hookup wire the second time to eliminate any slop in the connection. Once I’d done that the resistance readings were steady when moving the print bed around and jiggling the wiring loom.
Support suggested that I try to print using Cura itself rather than Octoprint.
So, I’ve done 3 prints with a laptop directly connected to the printer and did not observe the same issue. I’m going to do exactly the same thing with the Octoprint on the Raspberry Pi to see if the problem returns.
As a side note: I think my PEI sheet might be on its last legs…
Also: Do you sell replacement hot-end fans? Mine seems to have developed a rattle… I can’t see one on the online shop. And I should point out that the “Printer Chassis” category pages currently shows no products in it…
The heatbed patterns you shared earlier suggested (to me) an intermittent connector somewhere. If that was the case then disconnecting to take measurements and reconnecting may have been the fix.
You’ve done some thorough testing - so you are all set now for longer prints.