I just fixed a 1050 with a bad floppy drive controller chip. Symptoms were cyclic starting and stopping drives motor. Cycle time approx 10s. Stepper did not move at all. I did some basic troubleshooting and found out that logic part probably works. I found replacement FDC chip on eBay from Poland. The drive badly needed cleaning and lubricating. Rotation speed was also off. Works like a charm now.