to add to what BenzAir said-
The bulb holders can be found at the top of the cluster, the largest knobs. They can be found approximately midway from the center of the cluster, right and left. Twist I think a 1/4 turn to take out. The bulbs sit inside the holder and pull straight out of the holder. Replace both bulbs while you are there with stock spec'd bulbs.
You shouldn't have to disconnect the speedo cable since you are just going after the bulbs.
Mercedes does have a tool, that when used together help pull the cluster out that is basically held in by friction. The tools have handles at one end in the form of a T and at the other end little 90 degree hooks. You could make your own out of stout coat hanger wire.
There is a specific location to have the hooks pull on the back of the cluster. When you look at the cluster, where either vertical side turns and goes inward, at that location is where the hooks are to grab.
Some people use their fingers, others use dull blades, others reach under the dash and try to push it out from behind.
Remember it is made out of plastic, so a little at a time is the best way.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)