OK, let's see if I can get to everything here (and thanks so much everyone!!)
I was using a mix of bobbins I bought that were said to be used in Janome machines and a few Janomes that came in the package with my machine, but after the checking the machine last month he said to use Janome bobbins only, so that's what I've been using since then. I do also check the bobbins every time I fill them now, rolling them on the table to make sure they don't wobble or do anything weird. They did ask me if I've ever used prewound bobbins and I said no, they never really said if it's better or not.
My work surface is my dinning room table, it is stable when going slow, and moves a bit when I hit one speed, but when I go a tiny tiny bit faster it stops the movement, it's weird, it's only one speed it does this with!
They were going to try a new bobbin case but didn't have one in stock at the time I took it in. I did feel around every single little part of it and nothing has anything that can snag fabric. I'll try to post photos of the damage from the needle on that white area. I did feel it and it's there, but not horribly rough, but thread can't snag down there can it?? The bouncing seems to be the case itself not the bobbin.
The repair guy wants me to take a video of it, but I haven't figured out how to do that just yet. I think I'll need my husband to do it for me since I don't think I can get the right angle with a tripod.
It does this with thick fabric and thin fabric, it does it when going fast (like I said above I don't go super fast since I can't control the fabric when it goes too fast so I have it set to the middle speed with that switch thingy) and yesterday I was trying to pay more attention to when it does it and it does it slow too, not super slow, but what I would call slower average speed. So basically it's doing it all the time no matter what I'm doing. The weird part is when I start sewing it's totally fine, then after going for a bit it starts up. Like if I'm piecing an 6" square it's fine, but if I move to a longer seam, like 10-15+" it starts bouncing. Sometimes I can sew for a full length seam and nothing, then then next one 8-10" into it it starts acting up. I could maybe understand it if it did it all the time, but it doesn't.
Another quick question, like I said above I went from coats and clark thread from joanns to aurifil, and now I'm cleaning lint from the bobbin area about 5 times as often. Is it normal for the cotton thread to produce THAT much more lint?!