Better motor for spacerail level2

I wanted slower and much more silent motor for my Spacerail toy. Original motor that comes with Spacerail is loud as hell, picture below

http://img.dxcdn.com/productimages/sku_33400_3.jpg

I did manage to use small stepper motor (28YBJ-48 Stepper Motor) that connects by ULN2003 to Arduino nano and runs from 5V supply. Due to motor height some modifications are needed to original spacerail. Both ULN2003 and 28YBJ-48 can be found on Ebay easily.

Original Arduino code that i have used can b