We'll assume it's the W124.
First,Original Fuses? Throw them away and get a New set of Ceramic fuses.
With copper. (You have P.M. Traffic)
The "Bullet" fuses have a nasty habit of "Looking" good ,YET have Microscopic
cracks.
Gently, clean the fuse holders
(I use super fine Bronze wool , no scratches,dis-connect the Battery FIRST.)
ALL Kinds of Diagnostics in the Search function under Arthur Dalton's moniker.
I.E. :
http://www.peachparts.com/shopforum/search.php?searchid=4999048