Originally Posted by MFord

Drench it with good quality sewing machine oil, anywhere that two metal surfaces contact each other. Put a piece of cloth or paper towel under the feed dog to pick up excess oil. Then wait a few days and try again - should make a difference! If not, you can try wiggling the handwheel back and forth, lightly, while running a hot hair dryer in the stuck up area as it could be hardened grease. Also, have you been completely through the bobbin assembly looking for stray threads, even invisible thread? That can cause a world of problems. Good luck!