Hi,
The printer worked perfectly fine until I decided to upgrade to 1.4. Followed the instructions in the manual.
After upgrade it started to misprint and the printer head moved erratic while printing. Reverted back to 1.1.
Unfortunately the erratic behaviour is still present. A perfectly fine and great functioning machine now is useless!
Any ideas?
It sounds like you are talking about the firmware.
If so did you preform the procedure described in this link?
http://forum.velleman.eu/viewtopic.php?f=61&t=15455
Yes, all procedures performed as described and Arduino software 1.0.6 was used.
The strange part is that it works occasionally and then the weird movements starts.
I’m wondering if the drivers overheat. I have to check voltages again to see if I have made a mistake in measurement.
But I have made a complete 160 minute print without problems and then the problems started again immediately after starting a new print.
So overheating or wrong voltage might not be the case.
Is it acting up on just one axis?
Unfortunately not, both X and Y misbehaves.
It’s like the printer somehow gets the wrong information on how the print is supposed to look like.
One layer can be good and then the next layer is printed to small but correct size and then next layer is distorted and the forth in the wrong place.
And then suddenly a print can be performed flawlessly and I don’t know why because nothing is changed.
I just run on the standard Simplify3D settings that has worked for a week before. The only conclusion is that something has happened in the 1.4 flash.
This remained after reverting to 1.1 again. I’m not that familiar with Arduino but I’m trying to learn in between all work and family matters 
Is it possible to wipe (format) the mainboard before flashing?
Solved:
Apparently both pulleys to X and Y had come loose coinciding with my flashing of the FW hence I deduced the flashing was the problem.
Sorry for the confusion.
No problem at all.
Glad you got it sorted out.