If you've posted an attachment, and then tried to post the same picture from your computer (or a URL) again somewhere else on the FTE Forums - you probably got a message saying "You have already posted this image as an attachment in 'such-and-such' thread", and it won't let you upload it again...
NOT TO WORRY!
1) Go into your User CP
2) Look to the bottom of the menu on the left of your User CP screen
3) Click the menu item labelled "Attachments"
4) Find the one you want to post, and click it. (Or RIGHT click the link, and copy the shortcut)
5) Copy the address from your browsers address bar (If you didn't copy the shortcut, as above)
6) PASTE the link in the post you want it in, and surround it with image tags -OR- if using the advanced post window, click the tab for inserting an image, and paste the copied shortcut in THERE...
You've just recycled an old attachment
* I noticed this just last month, it may be a new option
Here's the living proof:
Compare the two images! If you right click and select "PROPERTIES" on each of them, you'll find them the same.
This is excellent to know about when you want to share a wiring diagram, or anything similar.