Jim, I don't quite understand what you mean by "extra spool pin through the round tray"? If I put the spool pin in the hole on top of the machine, then the spool is horizontal. And do you mean to put the felt onto the pin before the thread spool, or something else?
Jan in MD - MC12000
Answering from a horizontal position, Jim says:
The extra spool pin on the 12000 is completely different from that on the 15000. As you noted, it's horizontal and will not be any better for feeding metallic than the optional vertical stand on the back of the machine. The 15000 has a pin that goes into the machine vertically and comes with a tray that goes under the pin.
For the 12000 a good substitute would be a 3rd party vertical spool stand with a long "antenna" that the thread can go through. Taking metallic thread over a large distance tends to mitigate the knotting problem and will help with breakage.