That's it right there. Plastic shavings means pinchwheel is failing. You need to either get a new pinchwheel or adjust the tension on it, I don't know your specific machine but those are the only two options really. The only thing that worked for me with a worn out pinhwheel was printing very slowly, it can keep up with 15 mm/sec infill, anything above that and it would slip. It's slow, but it least it prints. I bought 2 brand new pinchwheels and I will install one in the next few days. I'll let you know what happens.