My stepson has an 86 420SEL that had just over 100,000 miles when I bought it. After reading this forum I checked and the guides were broken but thankfully hadn't caused the chain to jump, pieces were stuck between the up and down side of the chain just waiting to do some damage. Roncallo gave me step by step instructions here: http://www.peachparts.com/shopforum/showthread.php?t=118575&highlight=420sel

I ended up getting an indy to do the work as I couldn't pull the pins using the bolt/washer method. I also had the valve stem seals, timing chain & tensioner replaced at the same time.

Car's in the shop again today, exhaust had a hole in it. Just got a call saying it's plugged somewhere behind the catalytic convertor as well. Nuts, there goes almost another kilo buck!