I am highly suspicious of the thread, since it came from the original owner who was never able to get the hang of using the machine (perhaps because she encountered the same jamming problem?). I would also highly recommend using a good quality thread net on the cone. A thread net helps the thread feed evenly to the machine. Superior Threads has the best quality thread nets, better than others I have purchased.
Can you have someone else quilt while you watch the thread? Or set up a video camera while you quilt so you can review how the thread feeds. You may be able to see something that happens right before the machine jams.
Assuming the bobbin assembly is correct, and that you are using at least a size 90/14 needle of the correct type, the prime suspect is the thread and how it feeds through the upper part of the machine -- from the cone to the needle.
I found the Yahoo group for Bailey:
https://groups.yahoo.com/neo/groups/...gmachines/info