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Yes there is a G92 E0 before the code I pasted in.

Looking through the Gcode for the print there is this near the beginning: G1 F6600 E0
Could this be extruding at high speed backwards from a pre-set extruder setting (something above 0)?

I have just finished constructing and calibrating my Rostock Max V2, it heats, moves, extrudes perfectly under manual control but when I come to print the fan shrouds the stepper for the extruder runs backwards at high speed for a couple of seconds before starting to run forwards at a normal speed ...

Yep that fixed my problem with the control knob, now ill just wait to find out what other problem it has no doubt caused me

Yes that it correct.

HI there, I have just finished putting my Rostock Max V2 together, got arduino IDE and matter control as well as the USB drivers all installed and uploaded the repetier 091 firmware to the board. Everything seems to be working fine, the temperature tests, movement tests, end stops etc. are all good ...