That's a 1979 model. The Sears model number would be 217.585831. With that, you can look up exploded view parts diagrams at www.searspartsdirect.com. Some parts are available there, including your carburetor knob. You'll find it in the powerhead assembly list.
There is no air cleaner assembly on that outboard, or on most outboards.
If your motor has been performing well for you dig in and spruce her up.
If she is a long idle hand me down expect a long hard climb that may you not comeplete.
