Hi Martin,
I do not use eyelet ribbons on my SM3, SM4, SM7's. Just keep the reversing mechanisms very clean.
I think the SM7 is very much alike with the SM4...except with body styling and cowlings.
The SM3 and SM5 have manually set Tab stops. The SM4 and the SM7 have the key-top Tab set and clear buttons. SM2 has no Tab functions at all.
Not sure what the SM Service Manual you mentioned contains...but there are some differences amongst these SM's to keep in mind.
FWIW...
My SM3 weighs 14.6 lbs.
My SM4 weighs 14.8 lbs.
My two SM7's weigh 15.2 lbs, each.
Weights above do not include their case weights.