Not used the printer for a couple of weeks and it seems that whatever I print it is getting stuck. It does the outer perimeter OK then starts doing the first layer but after about 10 passes it gets stuck, it is not stopping but going over and over the same line apparently for ever. It took about 10 minutes to register that the sounds from the printer were not changing and this is what it had printed.

Tried a different STL and the same thing but it does seems that existing X3G files are printing OK. This is not something I have ever seen before.

More investigation required, has anyone else seen one do this?