Marklin’s BR 10 steam locomotives 8888 + 8889 were released with 3 pole motors, today the 5 pole motor upgrade is possible and relatively easy. Side by side comparison of the 3 pole (262700-clear casing) and 5 pole (E211911-black casing) motors:

This loco design features a fairly heavy cast metal shell that performs well putting weight on the wheels and giving excellent tractive effort. Does this loco benefit from the motor upgrade? This is one of those locos that runs great with 3 pole, but the 5 pole will be a little bit better slow throttle and a bit more quiet. The repair is quick for those with a little experience and patience.

The shell is removed by first gently prying off cap that conceals screw followed by removing screw.

The motor capacitor wires are always soldered to the chassis pick-ups, with soldering iron apply heat and remove original solder points.

Remove top and bottom screws that hold motor in place. Slide off old motor. If floating gear on pin  is pulled out carefully turn until gearing engages with wheel gears. Slide opposite end of pin into brass bushing of new motor and carefully engage gears with the motor gear.

Secure top and bottom screws and resolder capacitor wires and chassis electrical pick-ups. Notice side rods are held in place after securing shell, it maybe a little tricky at first to place side rods correctly before attaching shell. Note: one side rod on each side is always stationary and held in place by sliding onto post in frame (red plastic), the other side rod on each side is held in a channel below the other side rod.

Carefully holding both pairs of side rods in place while attaching shell is the only method for achieving success, you may need to try this several times to achieve the awkward coordination needed. Note: front of shell always goes on first.