Rebecca, sorry that your poor Matilda has to go to the doctor! Did the previous owner say whether the machine had sat unused for a while, sometimes if a machine hasn't been used in a while; it will work fine for a period of time then it just stopped. May need a tune up, just like us when we sit in one spot too long; its real hard to get going again!!!
Carol, hope your machine doesn't need the motor. Mine was still under warranty so I wasn't too concerned about repair cost. The biggest problem was the dealer would have had to order a new feeddog motor, luckily it was just lint!
I know I took off the bobbin cover and throat plate, checked out the bobbin area for any dust bunnies but never thought of lint collecting in the feeddogs and like the dealer said I would have had to turn the machine around to find the buildup; and she don't find it till one of her workers walked up to the machine at its backside and pointed out the collection of lint. She had never seen lint collect there and told me she had learned something new.
Just glad to get my machine home and working again. I sew too much to have my main machine in the shop. Have a traveling machine but its not the workhorse like the Emerald is.