This is an excellent write up - thank you for sharing. And this made me check - I have 3 SG1s - two of them are completely missing these washers and the third that I haven't spent much time on has one that is completely crushed and one that is replaced with a piece of cork. As you point out on the SM machines these washers can when they deteriorate prevent the machine from working - on my SG1s I have had no issues and as they work just fine I never checked these washers. So now I have to put them in. It could seem that all SG1 machines need some care in this area.