My singer cylinder arm 153w102 (recently purchased) keeps slipping out of timing. Could the reason for this be because the safety clutch shaft is frozen? The catch dog on the shaft doesn’t appear to be engaged fully and when I use the safety clutch release button on the cylinder arm, it doesn’t do anything. Thanks to Uwe and his videos, I have put it back into the timing a couple times. Thank you for any ideas that you might have about this. Kidkowboy