I replaced the stock tensioner shoe in my primary at 120,000 miles, it showed very little wear, but I had already bought the new shoe before I tore into the primary so I changed it.

 

Once the chain outer links groove in, the rollers roll. Wear stops on the manual one. I got 4 of the auto ones. Mine was free. The new model with the relieved teeth. Installed 3 including mine. Two people have no complaints. I took mine out because it was just too tight for my liking. I sold the other on ebay and the gentlemen paid to have it installed and few weeks later paid to have it removed. Guess it's like a boob job, some love it and some don't. I sure won't put any more in. Mine is hanging on the wall of shame. My original manual one at 40K still looks good. However I have run out the the auto cannot live with. One thing I did figure out is to really see the play requires you to push a lot harder then you normally would with a manual adjuster since the auto one has two strong coil springs pushing up. You almost have to have primary cover off to push hard enough to see it. What looks like only 1/4" play really is 1/2". Still pretty tight especially with my run out. I got some run out out by indexing splines but my primary chain probably needs replaced since it must have uneven wear. My actual crank spline runs true spinning on the bearings Well within .001-.0015