My 190E started ticking from the valve cover. The mechanic says it is time for a new cam because I have reground the old one beyond its service limits. He also said that the rockers will also need to be replaced due to a new hardened cam material. What all should I replace when I am doing this. Should be fairly straight forward right? I had a valve job and resurfaced the head 2 years ago, so the rest of the parts should be OK, right? It seems to run great except for the ticking. BTW, I have 255,000 miles on it.