Found an informative thread on how to use the official Mercedes EPC site

[funola]

Originally Posted by Graham

Just go to eBay and search for Mercedes WIS EPC. Auctions for DVDs will come up. They might say 1986-201x, but that only applies to the WIS part. EPC works for all years. Cost under $20 and work perfectly including ability to enter your car's VIN. No need to renew each year!

An example: https://www.ebay.com/itm/Mercedes-WIS-ASRA-EPC-Service-Repair-Workshop-Manual-1986-2017-/261923150768?fits=Make%3AMercedes-Benz

I often find the online EPC sites difficult to navigate. Is using the CD set you linked to easier? Do you have a set? As a test, can you look up and post the p/n for the o-ring on the rack damper bolt for a 1985 300D and how long it takes you to find it?

I tried to do that on the online catalogs and was unable to find that o-ring so far.