Leapfrog Creatr HS stops mid print (extruders not clogged)
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