Seat Back adjustment too loose

[TheSecondChris]

I have a small issue with my passenger side seat. How is the seat back tightness adjusted on the early cars with no electronics (totally manual) like on my 84? I see a big screw on the inboard side but I can't think of a good way to tighten this and not sure if this is the correct method. It's the big ugly rusty screw in the photo below. I didn't realize how bad it looked until taking this picture so I'll probably clean it up regardless.

The adjustment mechanism dial on the outboard side works perfectly but it's a little too loose so that the seatback begins to recline by itself over the course of a few weeks.

My seats were disassembled, recovered, and reassembled during previous ownership so perhaps something was not perfectly tightened during reassembly.

Thanks for the help!

[944 Ecology]

No adjustment. If left alone, the pressure from your back will tend to push the seatback down, and, consequently, rotate the knob. Ah the joys of owning an analog car.