GAngus
Be sure to release the shift key when you close the spline ring. If you close a spline ring with the shift key pressed the ring will not be properly closed. Instead of one cp at that point you will have two.
You can open and close the end point again by selecting it, pressing Shift/K, to disconnect it, and then closing it again by selecting it again with the left mouse button and, while still holding down the left mouse button, right click on the cp. I hope that you can make sense of that!
I know it is a real pain at times! I spent about a half an hour last night trying to close a 5-point patch.

Is that a fact? I haven't used a Mac for several years and am a bit out of touch but I thought these Wink files would run on a Mac. Okay, you would need a two/three button mouse and you would need to replace the 'Ctrl' key with the Cloverleaf key, or whatever it's called, but SWF files must surely run on Macs, don't they?