I sure hope you don't have to take it to an Elna repair person. Take a pocket full of money with you. I love the Elna to the moon and back, but I am a very particular and careful sewer. When you buy one from someone who doesn't know much about what she is using, you will run into problems like that. I have a Carina that I bought from someone who didn't even have the sense to bring along the air and foot controls--and they COST A LOT when you go about trying to find them to replace. I am not sure I would even attempt what someone has suggested to you about the gear mechanism.
Maybe someone who is familiar with Elna can work you through it. Best of luck.