We're running a Robox printer currently with White PLA Material. When we switched from the green ABS we ran the purge a few times until no more green could be seen. We're on our second roll of white PLA and even now very oOccasionally get a speck of the green ABS come through which doesn't stick to the white and causes a failure in the print. Has anybody else seen this? I guess there must be some ABS hiding in there that a few purges haven't shifted, maybe a purge at a higher temperature would help?