I have used a Labelle 107 oil for lubricating postwar locomotives.
Your owners manual pointed out the locations to use a drop or two of oil at the wheels and gease on the external drive gears . I have used a Labelle 106 for this . Both of these are modern products and plastic compatible.
On the Power truck sides , you will see a loction on either side where shaft having a gear inside comes through the truck frame. Add a drop or two of the oil at the shaft ends that are visible.
When you remove the cover of the locomotive removing the screws at the end of the body, you will expose the motor . If the internal gear grease is pliable, you should be able to turn the motor armature by hand . The trucks wheels will move also.
The top of the motor has a oil location and pad at the top bearing location where comes into the brush plate, Apply a drop or two at the bearing . It will soak through the pas as well. The Labelle 107 has a needle point oiler so you will be able to reach the lower motor bearing without removing the motor from the truck, Put a drop or two down in the bearing area. You can turn the motor armature by hand now and you might notice the armature turning more freely at this point.
You can try place ng the engine chassis o the track at this point and see how it runs. The operation should get freer as the engine runs a bit back and forth . You can also see if the lamps at each end are working and replace as needed .
If the armature is not free when turning by hand , you may have to remove the motor from the truck . As the oil penetrates , it may improve things here so give it a couple of minutes If the internal grease needs replaced, there is a screw holding the motor in place in the bottom of the truck frame. Clean any hardened grease and replace . You can use the Labelle 106 product.
Hope this helps
By the way it is a real nice looking loco. Enjoy
