Uploaded images don't display

Unless you provide a link to a page demonstrating the problem, no one will be able to offer much in the way of assistance.

Check if “Store uploads in this folder” url is correct in Settings > Media.

Thanks for spotting my mistake….here’s the link.

https://www.portablevalveactuator.com

Can you see the image in the wp-admin twentyten Custom Header page?

Somehow the image url is https://www.portablevalveactuator.com//2011/07/Header_Valves2.jpg while it should be https://www.portablevalveactuator.com/wp-content/uploads/2011/07/Header_Valves2.jpg

keesiemeijer is probably correct, you likely need to check your “store uploads in this folder” under Settings > Media because if you have a look at the source on the url above the header image path looks like this:

https://www.portablevalveactuator.com//2011/07/Header_Valves2.jpg

it should look like this (you can enter the following url and you’ll see your image):

https://www.portablevalveactuator.com/wp-content/uploads/2011/07/Header_Valves2.jpg

Notice that the image path as it is currently set is missing the “wp-content/uploads” part.

The media settings show that uploads are stored in the folder you have indicated i.e. default folder wp-content/uploads.

That seems correct.
Is the uploaded image width equal or larger than 940 pixels?
Can you see the image in the wp-admin twentyten Custom Header page (Appearance > Header)?
try resaving your permalink structure under Appearance > Permalinks.

Is the actual input field on “store uploads in this folder” blank followed by the italic text “default is wp-content/uploads or is there something entered in that field?

If it is blank try entering wp-content/uploads then save changes.