If there is a slight difference in how well the lids are punched or in the sprocket spacing, then the TD might be right on the edge of working ok with one tape but not the other. 

1) Line up the sprocket dimples and look at the tapes from the bottom to compare. 

2) Compare the tapes in the TD while turning its motor by hand and watching the sensing fingers. Are they centered in both sets of lids?

3) Wave a chicken bone over the KTR while chanting “epytelet, epytelet, skokie” three times…

Good luck

Nick