See if your raw material PVC is deformed or not. When you want to produce a process, you need to use a molding fixture for molding, which is usually caused by a process. It is impossible for people to make the wall thickness of soft abrasives different.

But you can have a look.

Also, changing the horizontal table is more stable.

Maybe your screw metering is small, material temperature and so on!

Try playing with the machine. There should be no problem.

If it still doesn't work, we should consider increasing the intake or changing the double intake.