Guinea pig not coming out of tunnel

[gmsong]

So basically I have a tunnel for my guinea pigs and it's getting really dirty inside I would like to clean it, but my guinea pigs won't come out. It's getting really annoying and the problem is not that they are shy. They come out when I'm not there and when I am there they are in the tunnel again. How can I make them come out with dumping them out of the tunnel?

 

[Swissgreys]

Scatter feed their fresh veg around the cage - a bit of fresh food always lures my greedy lot out!