I have three of those , they are called dometops, I do not have but one key, before I got the one with the key a small screwdriver inserted into the hole and turned just like a key and it will open, the key thingy is just a turn lock very easy to open, I have had one of those machines for many years, back in polyster days, it did not go backwards and has the long shuttle bobbin, I made a lot of clothes on it , western shirts, like the little eveready bunny it never quits,