Leapfrog Creatr HS stops mid print (extruders not clogged) I have tried to print a 3D model with Creatr HS from Leapfrog. This print failed twice. The 3D model is the same, .gcode the same. Surprisingly it failed at different stage. Please look at the pictures. You can see the place where extruder was when print stopped.   

  

I checked the filament and extruders, it is NOT a problem here. Extruders are not clogged, filament is not tangled nor blocked. Stepper motors stopped working, anyway the display shows that print progresses.  

I have created a ticket for this issue on Leapfrog support page, but had an answer that this printer is no longer supported.
 Does anyone has an idea what could be the core of the problem?
EDIT
Today I have tried print again to observe and answer questions from the comments. Observations are:
- The process suddenly stops
- Hotend cools down (you can observe it on the picture below - I am using left extruder - as you can see it shows 24/0; 24 is actual hotend temp, 0 - wanted temperature )
- Display shows that print is progressing even faster than it would happen when everything is fine (maybe this is not important)  




EDIT2  

I have opened the printer to see what is happening inside. The electronics is divided into 2 PCBs. One is an 'heavy job workhorse' (drivers and some logics), the other is a Olimex A20-Olinuxino-Micro. The pendrive with .gcode is connected to this board as well as the display and control joystick (actually encoder).

One of the USB ports from Olinuxino is connected to 'workhorse' board. Next to the USB port here you can see Rx/Tx diodes.
Observations:
When the print is in active state, two Rx/Tx diodes located on workhorse PCB blinking occasionally (mainly when there is a print head direction change), what brings the suggestion, that the data comes from Olinuxino PCB. When the print stops, these two diodes are blinking rapidly. I am thinking that there is some problem with Olimex board (it is sending uncontrolled data or data is being send too quick).
Below you can see image of drivers board with Rx/Tx diodes continuously on. There is also another Rx/Tx pair and these are also both on. 

I'm going to do some search on Olinuxino board/system.  

EDIT 3
Finding: During board and temperature check I have found that the fan cooling bottom Olimex pcb is dead. I have took it out, connect to +24V and... no spinning.

I have replaced the fan to a new one. Also, I have created a 20mm box model for printing, sliced it and tried to print it. No success here. After 2 lines of print sudden stop and Rx/Tx blink. I have downloaded model of Marvin, sliced it and tried to print: all ok!
Also I want to know if the data is continuously fetched from USB or loaded to Olinuxino and then used to print. So, started the Marvin print, removed USB from Creatr HS and yes, the print continues until the end. I am thinking that the data must be stored in Olimex memory and then fetched and fed to drivers PCB. Question is: where in Olimex the data is stored? Is lack of fan (and possibly overheat) damaged it slightly? If this is stored in onboard NAND memory it could cause a problem after a long time - it has 100 000 write/erase cycles.

New board would be a solution, unfortunately Leapfrog ran out of them. Olimex is selling boards, will try to buy one. I hope that different revision will work.
I have solved the problem. After some investigation I have decided to connect directly to the drivers board. It needs to be disconnected from Olimex board and instead connected to the PC, then select 250kbps speed, COM port can be found through Device manager. I have used Repetier-Host in not Easy Mode and all possible messages turned on to see all possible messages. Then I prepared 20mm box to print and tried to print. After two lines voila! Error message: 

12:35:32.401 : N187 M105*41
12:35:32.841 : Error:0
12:35:32.841 : : Extruder switched off. MINTEMP triggered !
12:35:32.924 : Error:Printer stopped due to errors.  
Fix the error and use M999 to restart!. (Temperature is reset. Set it before restarting)  


Now I went for quick search and learned that this can be caused by intermittent fault of thermistor or its wiring. 

 So, I disconnected thermistor from the PCB and checked its resistance: 170kohm. Now, when I moved the extruders on X axis there was a particular position when thermistor resistance went to infinity. There is a connector in head which went loose. After refitting the printer is behaving correctly.
Summary:
It is a shame, that the display on this machine does not present any feedback from the drivers board. Also, the PC connectivity on the rear of this printer does not bring any clear information (rear USB is first connected to the Olimex PCB and then to the drivers PCB, some information from drivers PCB are lost). BTW: Leapfrog drivers board is an Arduino based Marlin firmware. Info sent to serial connection after connectivity established is: 

Leapfrog Firmware: 2.5  
Model: CreatrHS 
PROTOCOL_VERSION: 1.0 
FIRMWARE_NAME:Marlin V1; 
Extruder offset X: 15.23 Y: 0.02