prusa i3 top layer lower than perimeter

i print for a living and thought i had seen every problem a 3d printer could have. but NO, i havent


i run a large bank of prusa i3's 24/7 and have done so for years.

my printers require very little maintenance.

clean the tips every 2-3 months is about it


one of them (that has run around 30 spools since new a few months ago) has a problem.

the top layer (of any print) is "sunk down" lower than the perimeter walls.

i have replaced the entire mk8, the entire ramps system with drivers, z threaded rods and z motors and of course, firmware

i have resliced numerous times

nothing has done anything at all to help

i run only pla and have changed brands, temps, etc

i am ready to simply throw it away


any ideas before i do put it into the trash?

also, i only use cura 14.07

Swap the bed heater and sensor with one of the other machines.

can you post a picture? i'm not sure i understand your problem.

i have actually printed on a dead cold bed and it does the same thing