Thread gathering under and around the bobbin/plate

Question

I have a Janome Memorycraft 9000 when i thread the bobbin it's like it's catching on something and wont feed through.When I can get it to feed through I try sewing and it gathers underneath and goes around the black part that the bobbin sits in and makes horrible noises..Please help I have had it serviced and it work ok for a little while but is doing it again.Please help