Welcome, madebymle. There have been some errors in the Serial number lists. Sometimes the numbers are not very clear and sometimes misread. A picture would help. Also, you didn't say whether your machine is in a case or in a cabinet. There is a pdf located at
https://www.quiltingboard.com/attach...020-01-17-.pdf on how to post pictures. I believe that the file size is in error as it seems like the size generally needs to be reduced to be able to post.
A good source to identify which machine you have can be found at
https://www.sandman-collectibles.com...r-machines.htm
The differences between the 101 and the 99 are the size of the bed of the machine, the shape of the needle plate, the location of the stitch length regulator and the motor (either built into the back of the machine (101) or can easily be removed by a screw and bracket that are under the hand wheel (99). There are other differences, but those are the easiest to identify.
I'm attaching a picture of my 99 and it is in a case. I have circled where the knee lever inserts into the base. Mine is the lever with a round end, that inserts. There is also a type that has a flat bar, that inserts into the base.
Janey - Neat people never make the exciting discoveries I do.
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