A nest is basically a lot of needle threads under the needleplate. They don't usually end up -in- the bobbin, though they can "tie" the bobbin case to the needleplate. Lots of fun.
I've made nests in probably every color under the sun. I really hated that 290C I started on. In retrospect, it really wasn't the fault of the machine. I blame my dad.
He never let me take lessons or Home Ec, and just thought I'd figure the machine out. Keeping in mind that's before the Internet days.
That and I'd asked for a bike for my 10th birthday and got a sewing machine. Doomed from the start I tell ya!
Typically, a properly adjusted machine, with "Regular" thread, and average weight fabric will be between 3 - 5 on the upper tension.
That said, if someone's messed with the upper tensioner, or it has fuzz in it, or someone's adjusted the lower tension, this could be different. There's information in the manual about resetting the upper tension. It's intimidating the first time, but work through slowly, and you'll be fine.
Were the loops on the top or the bottom?
Bird's nests are top tension issues. Bottom thread problems usually just look like the thread isn't tight against the fabric, or the stitch makes its "knot" on the top side (too loose) or the bottom of the fabric (too tight). (Or at least that's the worst I've run into.)
Best the thread with 2 different colors while testing, so you can see what's happening.
One weird little trick I do when threading the needle thread is:
I know the manual says to thread with the pressure foot up, and I do, up to the tensioner. Once I've threaded through the tensioner, I put the foot down for a second, tug up on the thread coming into and out of the tensioner to make sure it's completely seated, then put the presser foot back up and resume threading. This makes sure that the tension is what it should be, and I don't have phantom problems from the tensioner not having a good grip on the thread.
Might help.