I agree with turning it off and letting it rest. I also would caution against canned air blowing thing where they shouldn't go.
I have 8900 and love it. I did have some problems with skipped stitches and it turned out to be the blue batik fabric I was sewing. It took a bit and much frustration before I figured it out. I switched to a microtex needle and that solved that problem.
I also had problems with my thread breaking. I found out it wasn't the machine but rather the thread was catching on a burr on the end of the spool and since this machine has a horizontal spool position every so often as it passed over that part of the spool it would catch and break. I turned the spool around and problem solved.
Make sure your bobbin is in the correct position. It's easy to put it in backward. Follow the little picture on the plastic cover.
If you changed the needle make sure the new one is inserted right. The flat part goes to the back.
If you have more than one machine that take different bobbins make sure you have the correct bobbin.
It's easy to get stressed out and frustrated when something doesn't go right, especially when you're working on a deadline. Relax and systematically go through things. I'm sure it is something that can be resolved. I've had very few issues with my machine.