Are you using parts from the same vendor, purchased in the same package? Just an FYI, radioshack's electric components are the rejects from vendors with more strict tolerances. In other words, if manufacturer A makes diodes for reseller B, reseller B mandates that the diodes performance must fall within a certain range. If a batch of diodes fails to meet those requirements, reseller B will not accept them, instead they go to RadioShack to be sold for a lower price.
Now, you might not have purchased them from RadioShack, but perhaps a similar store. If you are using diodes from the same box, you could just have a bad batch. I doubt their packaging lists lot numbers, and I personally used parts from RadioShack w/o problems. However, there are likely 1000s of people who have performed this modification, and you seem to be the only one whose diodes are 'wearing out' so it might be worthwhile picking up a different set of diodes or the proposed BAT41 diode.
It's either this, you've done something wrong, or there's something wrong with your XBOX.
And in regards to your first post, I find it very unlikely that 750mA or more are pumping through those points. .75A is a shitload of current to be passing through this part of the board. The people that devised this hack are fairly competent and knowledgeable people, I doubt they'd make a mistake like specifying the incorrect parts after reverse engineering a state-of-the-art game console.
This post has been edited by craz3d: Jan 16 2010, 11:24 PM