I am having a lot of trouble with my tension. I am getting loops and "fur" on the back of the quilt!
My question is is it top or bobbin tension that is the problem?

If the top thread is having issues on the back of the quilt, it is probably the bobbin tension.
If the bobbin thread is having issues on the top of the quilt, it is probably the top thread tension.
One things to remember is that if you change the top tension, you may have to change the bobbin tension.
If you google adjusting the tension on a midarm or longarm you should get quite a few websites to read from. I really hate to change the bobbin tension, but sometimes you have to. I would start with the top tension. I hope this makes sense.
Good luck!

Did you remember to put the pressure foot down?

Is it a Pfaff??? I constantly had trouble with my midarm Pfaff. When you thread the machine, it's so closed in that you can't help but knock the tension knob...and it's VERY delicate. SO, I've had to write down where the tension is when I get it just right and look at that constantly. IF it's not the case as above -- did you remember to put the foot down?

If the problem is on the bottom of the quilt the solution lies in the top thread path. If the problem is on the top of the quilt the solution is in the bottom thread path.

Also, what thread are you using? Don't know about your machine but some only like certain threads....I know...all those wonderful threads and sometimes we can't use them. Try same thread in top and bobbin...cotton for some machines and poly works in others. I got best results with Isacord. And you don't find it everywhere. Also unthread everything and rethread....change needles if you think that might be an issue. Good luck. B

Could be both and could be the needle. Could also be the thread. It is hard to know with the information you provided.

It has to be one of the following:
Tension
Pressure foot up
Quilt is too tight on frame

I have a Pfaff Hobby Grand Quilter and had tons of problems until I figured out the above. Always do a test first before you start on the quilt, as each quilt sandwich is different.

I would rethread it and check to see if the bobbin thread has the right tension and rethread that also.

I had same prob this morning, took of feed dog cover and had a bunch of junk under there from sewing my husbands boat strap.

All better now.