Blackberry

Sometime back I posted about a problem with getting the metal cam off this machine. Well, I have tried several things and still I cannot get this metal cam off this machine. From the pictures in the manual it appears there is a screw in the center of the cam but there is no screw in this machine. It kind of looks like there are screw threads but the manual says it just pull off when the needle is in the top most part of the machine. Here are some pictures of the black metal cam. I am hoping someone on this board might have a solution for me or at least some ideas to try and get this metal cam off. Of course, it has to be on the machine for the internal cams to work so once I get it off I need to be able to get it back on. I would like to purchase some additional cams but haven't done so yet and won't until I can get this cam off. It doesn't exactly look like the one pictured in the manual but I am pretty sure this is the correct cam for this machine because the numbers seem to match Kenmore numbers. This cam seems to be more straight up and down instead of the curve shape as shown in the manual. The reverse lever is also missing but that is another issue that I am working on.