Might be a hot gas defrost system. A solenoid controlled valve reverses the flow of refrigerant. The heat normally pumped to the condenser is now directed to the evaporator, assuming this is a frost free freezer. Not sure that was done in 1957.
If you rotate the main pulley and lift the agitate plunger so that it engages the agitator you might find it easier to get that screw out, since the agitator is in gear and will not turn.
Trying to clean out my parts inventory. I do have some FF parts....tranny boots, pumps, motors, 1 & 2 speed clutches etc. Plus parts for other brands from the 1980's or so.
So true......as a family we had the 1964 Lady Kenmore washer in coppertone.It was THE
most beautiful console I had ever seen up to that point in my life. Sears had the most talented designers. We also had a 1966 french door bottom refrig designed by Sundberg Ferrera.