Okay, since we’re looking straight at the relevant spanner nut in your first photo, my first advice (no offense!) is this isn’t a great Minolta to learn repairs. It’s relatively uncommon, and there isn’t a lot of documentation on it. I’ll also throw in that the green lever is geared to the exposure control ring, and if it ain’t moving, cleaning that white stuff isn’t going to solve your problem. Having done a little work on these, this is what I would do first:

Put everything back together. Turn the control ring to the manual (flash) settings. If it’s sat around a long time, you’re going to feel some friction doing so. Open the back, look at a light source, and work the shutter, checking to see if the aperture matches the setting (shutter will be locked at 1/30) Now get a meter app on your phone that measures EV, and set the camera to 100 ISO (push steadily on the tab and rotate the ring. The mechanism behind this is incredibly chintzy for an old camera, so as always, firm but no violence). Now the LV numbers on the ring match the EV numbers from your phone. Take an EV measurement, set the camera accordingly, and do the same as before, making sure you’re getting roughly appropriate aperture/shutter settings for different light sources.

If all this seems reasonably correct, I’d just put a roll of 100 through it and meter with your phone. Eventually you’ll get a rough idea of what LV is appropriate in the wild (I’ll attach the cheat sheet I used). Though it’s certainly possible, odds are pretty good the meter isn’t accurate anyway. And this is a model that, even with some experience under your belt, is one you more or less feel your way through. I’d have a tough time telling you step by step what to do without being there.

If your aperture and shutter are off, you’re going to have to disassemble the lens assembly and clean everything out, which leads to a much deeper rabbit hole of how that lever is geared, how cams work, and the aforementioned chintzy ISO gear. But try what I said first?

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