Shark 9110

Question

I have a Shark 9110 and one day I was sewing and my machine got jammed.  So I stopped and I unthreaded the machine, cleaned the bobbin casing area and tightened the little s***w for the bobbin casing thing a bit.  When I rethreaded the machine I found that the top thread wasn't catching in the bobbin area, rendering machine pretty much useless since it doesn't create a stitch.  Everything else works perfectly fine... is there a way to fix it and not take it to a repair shop?