I know that the LED light failure in the dash displays is a very common problem in that vehicle and other Benzs that used the COMAND system/display. I've seen it
many times while researching the E's and CLK's from '00 to '02. It usually surfaces early though so most have been fixed under warranty. (unless low mileage to model yr like your prospect)
I wonder why the previous owner didn't have it fixed under warranty? Also I'm pretty sure (but not certain) that solving that display problem is not as simple as replacing bulbs. I think the whole cluster or at least a good portion of it needs to be replaced.
Good luck and let us know what you find out/end up doing.
