I am having problems with my old Bernina 830's remvoveable sewing bed. The interior cut out is worn down and it won't stay in place and keeps slipping. There appears to be a felt-like substance that had been around the inside but it is all gone. A techy told me that it was originally "horse hair"?
Any advice on how to repair or fix would be appreciated. I have to prop it up underneath with a small box to hold it level and in place with the machine's bed.