Need help! Thread keeps breaking on Viking Scandinavia

Hi,

I was wondering if anyone could help me.  I have a Viking Scandinavia 200, purchased about 8 months ago.  It seems to be working great, but sometimes, after sewing just fine for a while, I will start having all sorts of thread problems.

Here is what usually happens.  I am sewing along, usually in straight stitch.  All of a sudden, the machine will make sort of a clunking-ish noise, as if something is hitting the needle.  Then, the top thread breaks.  When I check the bottom of the piece I am sewing, the thread is all gathered up and bunched.

After this happens, I have tried cleaning the machine, rethreading, adjusting the tension, and nothing seems to help.  Eventually, it just goes away for a while.  I've also tried changing the needle, but that doesn't seem to help either.

I took the machine to a repair shop (but not a Viking dealer) and he said he didn't see anything wrong with the machine.  I have also tried different kinds of thread.  Last night I was using Gutterman 100% cotton, when this happened again.

Does anyone have any hints/tips?

Thanks,

Kristen

Hey, this sounds just like my machine about a month ago! 
I tried all the things you did as well and eventually resorted to using my old Singer.  Then I realized I had to bite the bullet and take my machine in.  My machine came back cleaned, oiled and best of all WORKING.  The problem was that somehow, the feed dogs were pushed too far down.  They had to raise it back up to whatever the correct specifications were, but it works wonderfully again!  Your repair guy may not have checked that area.  You can try taking it back and asking them to check it, but then again, they might not know what the correct height is for your machine so you may want to find a Viking dealer.
It's a weird problem I know, because the fabric still moves through the machine like nothing is wrong with the feed dogs.  All I know is that once it was adjusted correctly, I have absolutely no problems with my machine.  Oh, and my machine was just as old as yours when it started having issues.  Hmmm... must be a common problem.

What a coincidence, I came on here for advice for the EXACT same problem.  I have a Kenmore and chalked it up to the fact that its not a high-end model.  The manual suggests doing the same things, check bobbin tension, machine is threaded correctly, etc., but none of those have helped me either.  I'll try to take it in to get the feed dogs adjusted.  Thank you so much!!