Just wondering if anybody has issues with these plugs and their tips. Several times now on the current plugs, and my last set, the top silver piece on the end of the plug unscrews and backs off a little! Is this a common problem?

 

I had a few of them do that when I was doing my headers. I just took a pair of pliers and gently (read: I didn't crush it) tightened the tip back on 'til I was sure it wouldn't come back off. Haven't had any issues since.

 

I have been threw multiple spark plug changes and have used NGK tr55's each time. I have never had this issue or any other issues with them.

 

I have a set I am putting in my car...so don't take this too seriously, but...
I had a 98 S-10 that I put a set of TR-55VXs in, I am pretty sure it was when they first came out. Took me forever to get them, but anyways, I developed a really bad miss, and it turned out to be a plug. The all looked fine, and the gaps were right. What happened? I have no idea. I put a new set of Bosch regular platinums in and the truck drove fine. And yes, I checked all of the wires, and made sure they were plugged in right. I always assumed it was just one of those things that happens from time to time.