The top stitch is perfect but underneath the material there are many loops. I am assuming this is from the bobbin. How do I correct this?

Hi, make sure needle is not bent,is new and the correct size for the material used with correct stitch length and tension also.
make sure top and bobbin thread is not too old and that the same thread is in needle and bobbin. re thread needle. I have been sewing for many years but sometime accidentally thread the needle incorrectly. Good luck.:-)

Are you using old thread? Is the needle threaded correctly, is the thread the same in the bobbin as the top. Are the thread and needle the correct size for the material? Is the stitch length and tension correct for the material? :-)

what you describe indicates that the needle thread tension is too loose
it is not pulling the bobbin thread up and that is creating the birds nest under the material

normally it's assumed stitch looping underneath is a bobbin fault, it's most probably the top (needle) thread tensioner you should look at

Ok, Let's understand exactly what is going on. You said. "the top stitch is loose." So that we are clear....do you mean that you are getting loops on top of the seam? Or do you mean that you are getting wiggly stitches on top and small loops on the bottom of the seam? It's important to know... Because loops underneath means the top tension isn't right. Maybe you didn't thread with the presser foot in the UP position... or your tension is dialed too low.

Now, if you are getting loops on top of the seam... that means the top tension is too tight. Loosen the top tension. Make sure your bobbin is inserted correctly. If loosening top tension isn't enough, you may have to tighten the tension screw on the bobbin case/ or bobbin carrier.

Check the tension on your bobbin thread. When you hold it by the thread and let it dangle does it just drop down without any resistance at all? If so then you need to tighten it a bit. If the bobbin thread is too loose it can not pull the top thread down enough thus puts the loops on the top side of the stitch.

FYI---- Loops on the bottom-- problem is in the threading..
Loops on the top--- problem is with the bobbin.

Frist make sure that the bobbin is in correctly I know it sounds silly but check I have at least 2 machines a week or more come in and this is all that is wrong with them. if that is ok then check the bobbin case the black thing the bobbin sets in and see if it is nicked or damaged that is what normally causes this problem

ever tried adjusting the thread tension control? clean if possible
tighen it more, loose tension adjustment causes loose stitch and tangling of the thread.