well I've had think, and I reckon it's the vibration caused by the infill that's probably working the prints loose.

I can get rid of that for one part but not the other.

I'll dig out the glue stick and see if it makes any difference :-)

Failing that I'll stick blue tape back on. It might pull the tape off the bed, but the model being printed never came off the tape :-)

It's kind of got to the stage now where I don't care what the bloody things cost, they will be made !