The lenses in the Hi-Matic 9, Hi-Matic 7, and Hi-Matic 7s are based on the Minolta Chiyoda 5cm F1.8 Super-Rokkor.
I've had my Hi-Matic 9 since 1969. Added the 5cm F1.8 Super-Rokkor so I could have the same lens for my Leica.
The difference between the 45/1.7 and 45/1.8- probably in sample variation due to age. The 45/1.7 is every bit as good.
The Hi-Matic 9 adds follow-flash GN settings. Nice feature in the day of bulb flash and fixed output electronic flash.
A 1.5v Alkaline works fine. Test against a known good camera.
The lens and viewfinder of the Konica S3 and Minolta 7S-II are different. Take them apart and you can see for yourself.
The meter not working: does the Battery Test work? Does the follow-focus with the GN work?
I bought this camera in 1969, my first 35mm camera, and a whole Summer of mowing Lawns. I was 11. The viewfinder had enough haze built up to make focusing difficult- last CLA was 1976. Time to clean it, I'm a lot better at fixing cameras than I was in 1976. Tools required: Flat Head...
cameraderie.org
My original 1969 HM9 works perfectly.
Then I bought one "non-working" for $25 to get the Box and Lens cap I lost decades ago. Made it work. And another even cheaper. The Galvenometer was broken in that one. So made a best of two.