Both the motor body and the housing it goes into need to be smooth. You might try lightly filing the high rough spots. You might try wax or TopCote to make things slide easier. I would avoid any wet lubricants as they may eventually make their way to the wood. Absolutely do not use a silicone based lube.
I have a great Porter Cable Router (the motor can be swapped between a fixed
> base and a plunger) but after removing the router motor one day the aluminum
> casing got badly scratched and now, it is nearly impossible to slide the
> motor in and out of the plunge and fixed base. I lightly sanded the metal
> scars in the motor casing with some success but now I dread changing it ...
> Uggh. Would a light oil be recommended or a certain way of sanding or
> smoothing out the casing...
>
> Help...
>
> Thanks
>