" even if I should try!"
Yes, you should try. There is a stop screw in the clutch knob, loosen it, but be careful if you take it out all the way, they get lost easily. The clutch knob should spin off and there will be a washer underneath with at least one tang on it; note how it is positioned so you put it back on the same way. The hand wheel should spin freely on the shaft, yours likely isn't at all. Remove the hand wheel from the shaft, you may need some force to remove it. clean thoroughly the inside of the hand wheel which was on the shaft and the shaft itself. Most people use only sewing machine oil to clean it. On these parts I have taken very fine grit sandpaper, at least 220, and cleaned the shaft and the inside of the hand wheel. When reassembling oil the shaft first and then see if the hand wheel spins before any other reassembly.