For years the Soviet army didn’t care much for losses. The enemy was at the gate and had to be pushed back at all cost. If things could be easily salvaged or repaired, fine. But any more than that was just left to rot on the battlefield. This whole philosophy changed with the first vehicles derived from VK technology: even destroyed these were still very valuable. And even if nothing could be taken from the wreckage, it had to be properly destroyed so nothing would fall into enemy hands. This kind of job is much more seriously done outside of the battlefield.
Hence the creation of a new generation of KV47 with specialized task and equipment. With these, heavy SSU regiments could now take care of their precious vehicles directly during combat. And some of these models proved quite efficient to blow things up as well. The guys piloting these things are amongst the best mechanics on the planet. They already knew how to make pretty cheap but effective repairs with what they had at hand. But they know how to pilot a walker too.
The “Marlen”, officially model “I” has a Monkey Wrench and a Pincer. Primarily designed to follow the heaviest SSU land vehicles, this model is mostly found in Heavy Guards Tank Regiments. Most of its pilots have customized their walker to give it a little boost for when things get tough: those large SSU tanks draw a lot of nasty infantry around them.