Tj Rae

97k miles on a truck that has had perfect upkeep since bringing it off the lot, I found a stuck lifter about a week ago on #6 intake. No surprise that I happened, I was bummed but not shocked. I did the entire job myself as per GMs tsb, with all dealership oem parts, new guides and all new lifters across the bank. Cam looked perfect, bore looked untouched only real damage was tiny bit on the end of the pushrod smacking the rocker. Reassembled the motor and put maybe a .5 hour on the motor before I now a have a repeat failure in the same bore, I'm now halfway through the job again and I don't want to do this a third time. Any idea what could be causing it?