I would keep on cleaning and oiling. Being a bit stubborn is common. It's hard to pin point exactly where things are sticky, so oil every where, detect all oil points, add few drops of oil, turn the machine and repeat. Let it seep in over night and be patient. I had a sluggins machine that took me 4 days of repeated oiling and turning the mechanism before it freed up.
Remember to oil the point where the needle and presser bar moves up and down in the cast iron part of the head (behind the face plate). These places can take a bit of effort to sort out. Make sure the oil points on top are clean; poke down them with a tooth pick to unclog them. Take off all plates, covers, lids, clean and oil. It's usually more of the basic, and maybe finding a spot that's overlooked.
Last edited by Mickey2; 02-22-2019 at 04:58 PM.