Fix your Tensioner on Vintage Singer 201, 221 and 301

This video makes a recommendation for adjustment of the tensioner of a Singer 201 sewing machine. Other machines may have similar tensioners. The Singer 221 and Singer 301 got same issue.
List of contents
0:00 Intro
0:15 How to modify tensioner
0:44 Video of inside tensioner
1:03 The reason for the normal big variation in thread tension
2:50 How the unwanted variation us reduced
3:48 The important gauge to measure thread tension
4:30 End
The drop in variation of tension was verified by using a dynamometer. Furthermore, measurements are made at different positions of the tension discs (they are turned randomly). Before the change, the tension could vary a factor 2. After the change the tension vary a factor 1.2.
I suppose Singer realized at some point in time, that the 3 humps on the back of the -|+ cup was a bad idea. They were removed on the tensioners for the Singer 500A and 503A. I should call it a design flaw, but you do not know how often you will see the problem on a machine.
I made a survey by finding 23 Pictures of Singer 201 with clear Picture of the tensioner. 16 of them had the -|+ mark on 12 o'clock position. 7 had mark at other Places. So the room for improvement is there - so please share information for relevant partners.
I recommend the following videos not made by me regarding this tensioner.
This good video by Archaic Arcane provides good information about how to check proper operation of tensioner:
• Fast tension test - th...
This is about disassembly and reassembly. This can be to clean all the parts of the tensioner. This video is from SE MN Sewing Machines:
• Vintage SINGER Sewing ...
This video goes in more detail from Archaic Arcane
• Disassemble and Reasse...
Please like the video, if you get useful information. You will probably find other tips for your sewing machine on my TH-cam channel.