How do you fix a birds nest?

How to fix BIRD Nest

Reasons and Solutions:

Bird nesting typically occurs when the bobbin is not set properly: whether the tension is incorrect, the bobbin case is dirty, or the bobbin is not properly placed in the case.

Steps
1) Remove the excess thread from underneath the needle plate. To do this, you will probably have to cut away all of the nested thread with a pair of scissors.

2) Remove the bobbin and case from the rotary hook.

3) Remove the bobbin from the case.

4) Ensure the bobbin case is clean. Please refer to Tension Adjustment.

5) Once the bobbin case is clean, reinsert the bobbin and ensure the tension is correct. Please refer to the Adjust your Bobbin.

6) Next, you want to make sure the pre-tension is adjusted correctly. Please refer to the Pre-tensioners.

7) The last tension adjustment you want to make is to the main tension. Please refer to the Tension Set-up.