[pmiguel]

i doubt it's the TT.
My guess would be the bead linker. This used to degrade in the manual ePCR days from numerous freeze-thaws. It's much more likely a culprit than the TT.
I asked 3 other sites and the FAS, and there is no word of bad lots yet.

Maybe DNADEB will respond. But up thread they stated:

OLD Beads from the freezer stick fine when put in two quads of the same slide. Beads modified with the new kit and placed in the other two quads do not. UNLESS they are then RE-treated with the term transf from old kit.

No mention of using any reagents from the old kit, except terminal transferase. But, that may have been implied.

But it is clear that 3 new XD kits were tried and all of these failed. So I don't think freeze-thaws at DNADEB's site are likely culprits.

--
Phillip