Rat Cage For Guinea Pigs

Hi! things have been spinning around here! we where able to find a lady with a rat cage she wasn't using, so she gave it to us! she was (and still is) so generous! it is for the guinea pig(s) that we are hoping to get! here is the picture of how the cage is supposed to look:

but, ours dosn't look like that. the platforms are lowered so a guinea pig can clime up the ramps, and the lower platform and ramp are a little diffrent. the ramp is connected to the front rather then to the back, and we have a mettle lid over the bottom platform so that the guinea pig(s) don't fall through the hole, but is is a little slippery. please leave a comment if you have any ideas how to make it not quite so slippery.