Ive gotten the link to show up and work numerous times now and also tested that it stays all the way through to confirming payment, basically its just persistance.
This is what has worked for me:
1. Search for one of the key words that usually brings up % off results. Cheap camera, cheap wii, gold coin etc etc.
2. If you don't get the 25% on the 1st search just keep hitting F5 and within usually 10 refreshes you'll get a 25% link
3. Once you have the link, middle click (click the mouse wheel) it 10 times or so, as long as you're using a browser with tabs that will open the link in 10 different tabs.
4. Check the 10 tabs, its usually around a 50% chance that the cashback icon will show in one of them at least.
5. If not, middle click the cashback link another 10 times. Check. If you get to 30 with no cashback icon (hasnt happened to me but im sure its possible) you can try a different search term if you feel like its wasting your time.
6. This has worked for me 15+ times using 2 different computers and both Firefox 3 and IE7
Is it a hassle having to go through this to get it to work? Yes.
Is it worth the hassle to save up to $250x3 (or more if you're greedy and open multiple ebay accounts)? IMHO yes.