In my case, the chain was perfectly tight and I haven't had
any problems with the tensioner. I think I saw that the
tensioner will allow the chain to rattle especially as the
oil pressure builds up. Anyway, Landi took off the valve
covers and replaced the top rails. This was a total bill
of $250, but he did do a little more work on a broken stud.
Landi charges $60/hour. As he explained, it is the top rails
that shatter and fly into the cam gear. The lower guide is
not as big a risk, (statistically). I agreed so we had the
top guides done only. The lower guide would involve the whole
front engine components being removed and several more hours.
I am going to replace the entire chain, lower rails, tensioner
when it gets to 200K or if the water pump fails.