Singer 401a cam stack
Hi
I got a Singer 401a which was beyond filthy when I got it. I now have cleaned everything but the cam stack. I can unscrew 2 of the screws but the one at the 10 o'clock position (silver pillar on top) won't budge. I've soaked it with oil approx. 5 days to no avail. I don't want to strip it, but would like to clean in between the cams. Is it necessary to do this? At this point the straight stitch works great, but I can't produce nice designs. When I got the machine it was frozen solid, but all works like a charm now except for making anything with the cams. Any help is appreciated. Thanks in advance