Changing out an original 3 pole motor with the current 5 pole motor is easy for the Marklin Z rail buses.

Parts needed: Marklin 209452 (motor) and 89881 (brushes)

Notes: The shell of all Marklin Z rail buses slide of the chassis by very gently prying off from either end (Marklin illustrates pulling shell from center, I don’t find this works successfully), but use extreme caution as not to break those parts of the shell that extend out such as the buffers. A little gently prodding and pulling will do here. Nimble fingers and magnifying goggles plus one very small screwdriver is what is needed with this entire repair. No screws are used to hold trucks and internal framework to chassis instead Marklin devised a brilliant clip system that holds each in place securely. No circuit board in this loco instead electrical contacts have been installed within the clear plastic superstructure that incorporates the two headlamps, brushes, and traction contacts.

Step by step: 1. turn loco upside down, using a very small screwdriver gently insert of with small amount of pressure lift off truck housing exposing wheel set and small gear that engages with the worm drive transmission gear: give these gears a good cleaning in a solution of Original Windex (blue) and dry thoroughly  2. turn loco right side up and remove the two brushes and set aside  3. *stay clear of couplers (the objective is to leave coupler and springs installed in chassis during entire process) with very small slotted screwdriver very gently wiggle plastic superstructure from each of the four corners: equal small wiggles to each of the four corners: plastic housing is not removed at this point, it just needs to be freed from the metal hooks of the chassis (*careful not to break the plastic!!!) 4. with the plastic superstructure slightly elevated from the metal clips on the chassis frame begin the process of pinching the plastic clips (two pairs) located one third from each end respectively: disengaging these two sets of clips will allow the plastic superstructure to wiggle free from the chassis and thereby expose the motor  5. motor easily lifts out, give the chassis a cleaning, but do not use solvents of any kind to be safe and kind to the metal finish 6. the new 5 pole motor (#209452) slips into place and reassembly takes place in reverse order Notes: 1. brushes compatible with the new 5 pole motor are 89881 2. apply equal pressure to clip mounts during reassembly 3. wheel sets will need to engage with contacts putting one side on first at an angle and then the other works well for me (the rail buses are easy because each truck has only one axle)