Originally Posted by tryhard

Hello, out there. I recently bought a second hand Pfaff 1200 GQ, as I needed the throat space for FMQ. I just wanted to know if any one can help me with thread and bobbin combinations , needles, and tension.
The machine was sewing well, until I changed the thread to a Bottom Lin 60 wt poly , and have upset the tension . Any advice on how to fix this will be truly appreciated . Thanks in advance!