The Max Liebermann class 601 special one time series from 1997 is a two locomotive set that deserves a special highlight with regards to any under the hood repair. I just upgraded mine with new 5 pole motors, and it deserves some special considerations before you might consider doing the same. As with others in this series, Marklin continued to make changes and improvements including more durable couplers that allowed less gap between coaches and locos thereby making some parts non interchangeable between the 1st release of this loco type #8873 (DB) and the second release 88731 (DR). Those non interchangeable parts include the circuit boards and couplers all other parts are interchangeable through the series. The first coupler designed for the 8873 was a plastic clip with electrically conductive brass under spring tension, cars and powered end cars were simply pushed together gently until clip engaged with post located inside each car. The 88731 used a new design coupler that was flat with electrically conductive brass surrounding it and more surface area for electric transfer than the 8873. The new coupler necessitated the elimination of the center post in each car end which thereby led to a newly designed circuit board that would accept the newly designed couplers.

Please note before you make the motor upgrade to this set there are two distinguishing  remarks I would like to make that might be helpful: 1. one loco coupler is semi-permanent, it needs to be carefully released from the clip that holds it in place. Use gently pressure to wriggle up the opening in the loco shell and with little pressure slide out coupler. *Other coupler will simply slide out at the normal 90 degree angle that is used to couple cars and locos together in this set.  2. Marklin did not have their heads on straight when they assembled my set, they soldered the circuit board whiskers directly to the motor wires. I am not sure if this was widely done with this set, but this is the first I have seen it. In order to change the motor or do a strip down cleaning and re-oiling 4 solder points need to be removed (2 each powered end car). *Do not attempt to remove circuit board without removing the solder points first, motor is held in place under circuit board mounting plates held in place with 7 screws, it is impossible to remove motor and circuit board at the same time. In order to remove solder points heat them up with iron and pull wires away, remove any roughness of solder left on wires by gently heating residual solder with iron, bend wires back in place to make contact with new motor wires. *The down side to this repair are several opportunities to break parts or melt plastic parts with soldering iron. Not all three pole motors need to be replaced and maybe this is one.

Speaking from experience with a couple of 8873 sets, couplers used in this train work great, I have never had one break or malfunction.

“Good night, and good luck.”  -Edward R. Murrow