Mickey2

Two months? Has to be the worst case ever. You could try some kind of thin spray can oil, they often work differently than general sewing machine oil. I once turned to Finish Line Ceramic Wet Lube (bicycle oil) and it loosened a screw that had been stuck for (literally) years. I had tried all kinds of oils, but apparently it did it did the trick, and there's no special ingredient there that should loosen rusty screws better than other oils. My main point is; just try a different type of oil or lubricant, and keep at it.

I would also take out the needle, unscrew the needle plate and inspect the bobbin/feed dog area for anything that might be blocking the movement. Some times a bit of force is needed to get things unstuck, so wiggeling the hand wheel now and then is not a bad idea at all. If you can detect which gear, hinge or passage that's frozen up it makes special treatments easier. There's two black caps under the base, each held in place by three screws, take them off and inspect the gears under there if you haven't all ready, there might be something stuck between them.

I once had a machine stuck because of grime or rust in the needle bar shaft, the hole in the cast iron part behind the face plate. There were no visible signs until I started oiling, poking and forcing the movement. Double check with a tooth pick for clogged up oil points, all of them, build up of all kinds of grime, dust and lint are common.