I don't know the proper position for the needle on your machine. I have a very old, industrial machine that I inherited. I know nothing about it other than it sews like a dream. I was making a bag and broke a needle. After that, I couldn't get the needle to bring the bobbin thread up. I was frustrated for months. Just yesterday I called the machanist that makes house calls in our area to make an appointment to come and fix it. He asked what the problem was. I told him and he said it sounded like the needle wasn't in properly. I didn't even know there was a right/wrong way to put it in this machine because the needles are round on the top. Anyway, I put the needle in as he told me and now my machine is working properly again. I just knew it was something major. I was very pleased that he talked me through my problem and I didn't even have to pay a consulting fee.
So check your needle.