Luckily, the Yellowboy doesn't feed a lot of fouling back, much past the lifter. You would have to remove the sideplates (loosen the lever and lifter springs first) and drop out the lifter, clean that, and hose out the insides with Ballistol. You might even get along for a while just hosing it with Ballistol without disassembling it. The 73 is a lot easier to disassemble than the 66, and certainly easier than the Henry. I polish the ends if the lifter and lever springs where they contact the cams and the nose of the lifter arm where it contacts the inside of the lifter. Smooth the trigger and sear notch if needed, polish any rough spots on the lifter and white-grease the cavity the lifter nose goes into in the lifter. I also white grease the toggle links and the inside of the sideplates where the toggles might rub. The 66 is so smooth out of the box, it doesn't need much.