There's an excellent DIY on this site RE oil tubes.

If they're still ticking, you may have galling on the lifter faces - it'll show up as scratches and/or plain wear. Or even on the cam lobes. Surprisingly, there's enough oil slopping around up there that the lifters get [barely] enough oil to prevent destruction. I've never seen one that caused a failure, even one that had been driven with the problem for 50k miles. Just the wear you'd expect without direct lubrication.

Your noise may WELL be elsewhere. The most common spot is exhaust leaks. This makes a distinct ticking noise - especially if someone has had the manifold off, say to replace O2s or something. That gasket must be replaced whenever it's separated. Exh leaks can also be in the valve seats (although not as noisy), or even something real obvious like spark plug threads.

Last check is injectors. They'll make a similar tapping noise, although somewhat different. And they can be very loud in their final moments of life.

But remember - ALL 119s tick to a certain extent. A price to pay for the finest motor ever to be put into production