lervia kh 4000?

Hi
my machine has been great until it jammed and I couldn't move the wheel to move the needle up/down
I opened up the bobbin area and removed the grippers and the needle moved again put it all back easily( or so I thought) but now the top thread doesn't pick up the bobbin thread as this thread doesn't seem to go to where it can be picked up please can you help as it is such a super machine and I don't want to throw it away
Thanks