Could you take a couple of pictures of the lever you are talking about? I have a Nolting long arm and don't have any lever to start sewing with. I do know that if the needle is in the up position, then I can pull the thread through the tensioners fairly easily. If the needle is down or partially down, it becomes much harder.
I don't know why some sewing machine people have to be so ugly about questions. Somehow they have forgotten the art of "helping" a client. I would ask to speak to the manager. If you are close enough, it might help to take some pictures and videos and go into the shop. Maybe the person that spoke to you was having a bad day and didn't really mean to make you feel stupid.
Good luck with getting your machine sewing.
Edited to add: This manual does show your lever. I suspect that if it is swinging freely, you will have to make a repair. If you don't have any success locally, why don't you call Tin Lizzie? They would want you sewing and not sitting there with a machine that doesn't work. They might could send you the parts and instructions on how to change it.
https://www.sewingmachinesplus.com/m...ual_Feb_08.pdf