Mercedes uses "hydraulic compensators" under the end of the rocker arms, pumped up with oil, to hold the rocker to the camshaft. Perhaps this is only in my SEL model, and different in Bigshot's SEC, (big sedan vs. performance car). I only know about mine, it is all I have worked on! There are shims that go under the rocker, and can be changed. You need a go-no-go gauge to set the proper clearance when doing so.
I disagree with ignoring the ticking. Here is why: This could be the start of the rocker damaging the cam lobe, and you will go the route of Benzman above, replacing all the components in the valve actuating train. This is fine if it goes well, BUT the bolts holding the cam bearings go into the block, and sometimes threads pull out with the bolts. VERY bad! Then you get to remove the head to helicoil it!! So I think I would look into the source of the ticking, and replace the rocker if needed. Also, good practice to replace the oil tube plastic parts as a PM.
My $.02, take it for what it is worth.....
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)