Buy a lotto ticket.
Then do a search on chain guide and chain replacement. Easy job for a good DIYer, should be no problem to do over a weekend. If not a good DIYer, then the job is best left to a shop, preferably an independant as the cost will be less. Once the guides become brittle they often break, usually on start up, but can let go at speed. Once that happens expect the chain to jump and the result will be a destroyed left head (valves and cam for sure).
The topic has been covered several time with pictures and how tos. Memeber Thomaspin has the procedure well covered on his web site.
Be sure to do, or have done, the chain tensioner at the same time.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.