... threaten it with percussive persuasion... aka a large anesthetic mallet... aka something big and heavy
tl;dr Loose connections can be a pain. You don't want them!
So, my precious has been hard at work again, and with just two prints left to go before it could have a rest for a while, it decided to be a stubborn 'lil hitch... and b0rked a print three hours in... just stopped stone dead. I was out at the time, so I came back to see that, and thought perhaps it was a power brownout or something else weird that it didn't like... so I powered cycled it, and it booted up fine. So next day, lets try that again... it started up ok, and then about 90 mins in... same thing happened, just stopped in its tracks... and this time, I was around, and heard it just suddenly stop. So, lets go poking the button... nothing happened. Load up the computer, and check what flux studio says... but no delta to be found... wah? But, once again, it power cycled, and booted up fine. So lets do one more attempt, and then it gets the belly up and electric screwdriver treatment. And it b0rked within about 10 minutes... didn't even finish the first layer. So I know for certain something is really wrong with the 'ol girl, but not. what. So I whip out those screws as I now have time to strip it down, and go poking around in the innards...
So motors are working, filament sensor is disabled, extruder and hot end was working fine, so what could it be...? No chips looked fried on the motor control board, or the rPi... so that just leaves a loose connection, or is that damn microSD card playing up again? Nope, it's still firmly inserted, but on closer inspection on the raspberry pi interface connector, I spotted the problem... it looks like at least one of the connectors had worked its way out of the shroud, so must have been making intermittent connection as the machine vibrated and shook. So I unplugged it, reseated the loose connectors and plugged it back in firmly... and whatda know... last two prints were perfect, and it's hard at work on a few others I added to the build queue in the mean time