At 13 k mine started to let go, i replaced with S&S gear drive kit i got the kit, adjustable push rods and lifters on Ebay for 999.00 shipped item # 110865480578. the bike is smoother and has better throttle responce. here some info i found on thid problem

Recalls and other mechanical problems

Wear of cam tensioner shoes
The Twin Cam motor has cam chain tensioners with nylon composite shoes, and these have proven to be a wear item even though they are not on the regular maintenance schedule. Some riders have seen these shoes wear down until there was metal to metal contact against the cam chain, while others have experienced no wear. Harley-Davidson changed from spring loaded to hydraulically loaded tension on the shoes in the Dyna line for the 2006 model year and for all Twin Cams with the introduction of the 96ci Twin Cam for the 2007 model year. Some believe shoe wear and the variability of cam timing introduced by inconsistent tension on the cam chain continue to be an issue best resolved by third-party gear drive cam sets, such as those made by S&S Cycle and other aftermarket firms.
Recall - Cam retention bolts
In 1999 a recall was made to replace the bolts that hold the cams in place. The bolts were replaced with Grade 5 bolts to prevent a catastrophic shearing.
Excessive Heat
In order to comply with the ever-stricter EPA standards, all TC96 equipped Harleys come from the factory tuned very lean, which in turn creates a great deal of heat, and loss of power. All 07 and later Big Twins are equipped with Electronic Fuel Injection (EFI) and 02 sensors for closed-loop operation, allowing an extremely lean tune to be safely, and consistently achieved. This has been a topic of much discussion in the Harley world, as many have commented that the excessive heat makes the TC96 too uncomfortable to ride in stop and go traffic, or in the heat of the summer. There are also concerns about heat's impact on the longevity of the engine. To help combat this many owners re-tune their engines, run synthetic oil or add an oil cooler; the Motor Company has also redeveloped a "Parade" mode in which one cylinder shuts down on the Twin Cam to prevent damage to the engine.
There is some debate as to whether or not the heat issue was resolved on the 2008 models.

 

Gear-driven cam set-ups are great as long as the pinion shaft run-out is .003" or less, and STAYS that way.
Scott

 

I have 25000 on my 06 NT. Had the new hydrolic kit installed. Turns out my tentioners has some wear on them but not bad at all, I could have went another 7000 miles or so. But I sure do feel better knowing they were changed. If you guys wanted to know it cost me 860. 00 for the install at my dealer and they used my pushrods. Tech does not like to go with the adjustable ones.