How high are the levels? How many levels are there? Is the floor and levels solid, or are they made out of wire? Is the ramp wire?
What kind of bedding are you using?
I ask because most store bought cages are not good for guinea pigs. Wire bottoms, levels, and ramps will hurt their feet. Steep plastic ramps are usually too short and slippery. Very few of the store cages are of adequate size, if any.
It is usually better to build a new c&c cage or similar then to try and fix up a store bought one.
Another option is to replace the ramp with a tunnel. For borders, plain cardboard often works as a temporary solution. Coroplast is a good material for making all sorts of trays and sides.
Check out the ramps gallery for ideas. There are a lot of pictures.
http://www.guineapigcages.com/photos...ry.php/cat/509