I did mine on my 190E with a bead blaster. Despite much of it flaking off easily, other areas were stubborn, even with the bead blaster. I probably spent a couple of hours with the bead blaster. I re-finished it with engine enamel from a spray can after thoroughly degreasing it. Depending how well it lasts will determine if I do the same with the 300TE. The valve cover on it is not flaking yet as it was on the 190E, but does have a few blisters. This was a rotten finish that MB applied to these models. The earlier smooth natural alloy valve covers of the '60s and '70 looked (and lasted) much better. In addition to the poor finish of the M102 and M103 valve covers is the fact that (on the M102 at least) that they are prone to distortion. The casting finish is also poor with various holes and other defects. I believe these covers were magnesium rather than aluminium alloy which possibly had something to do with the problems. I priced a replacement, since apart from flaking paint and distortion mine also had a cracked plastic oil separator (not available separately). The price was rediculous. Mine now has a self-made metal oil separator (took a whole afternoon to fabricate) and the above mentioned engine enamel finish. The following thread has an engine bay pic of the finished result. You may notice my colour change as well.
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.