To bring this one to a bit of closure. The bearings installed by Trek are manufactured under Cane Creek license to VP Components. The product number is VP-A61ACK which comprises of two MH-P03M bearings. They are basically the cane creek 41 standard with one difference, the angles are 45/45degrees as opposed to their standard of 45/36 degrees. Bottom line is finding those bearings is a nightmare and if you do, they are way more expensive than they should be. Sounds like Trek did this for a few short years and then switched to the true cane creek standard.

The solution is to put an IS41/28.6 IS41/30 new headset in. Trek sells / lists the Headset IS41 as the replacement which uses standard cane creek 41 bearings. You can also install the Cane Creek 40 series or 110 series IS41 to replace the bearings.