[redmodelt]

Unless there has been some changes and suppliers have stock, the switch backs have been out of stock for a while. If the spider is not making contact and holding, the back may no longer be flat and detents are worn. Can be fixed. Lots of times the paper used is warped or coming a part. Once you get it apart maybe post some photos and we can try to make suggestions on the next step. Google "mtfca switch repair" I can't think of the guys name but there is someone that can rebuild it.