Need help with vectors for extrusion?

Hi everyone!

Have a bit of a dumb question here. I just want to make an extrusion of circles at different lengths following the normal of the surface divide. 

Right now, there's an attractor thing going on here where the closer the sphere is to the surface, the smaller the circle's radius. I'm trying to get the extrusion to be shorter for the circles closer to the spheres and longer extrusions when they are further away from the spheres.

I need to get the distance to plug into some vector component using the data from the 'n' outlet of surface divide and then back into extrude. Unless there's another way?

Here's my definition below:

And a screenshot

My rhino and grasshopper files are attached.

I will be really grateful if someone could help me :)

Cheers,

Ra