I had the same problem, they sat in the gutters and used their claws to dig thru the pine soffit and fascia boards, then into the attic they went. I borrowed a neighbor's pellet gun and crawled up into the attic, I had to lie there for a while before I saw it's little furry head silhouetted agains the backlight, then I popped him. I saw three more in the gutter when I went outside (fortunately when I hit him he ran, then promptly died and fell to the driveway, so I didn't have to clean him out of the attic) and very carefully shot them too. I think if you get the ones that are the problem, the rest don't try to follow the scent.
I put metal flashing over the wood they destroyed when I replaced it - they can't dig thru metal - I just painted it to match the rest of the trim and it doesn't show.
I bought my own pellet gun and spent the next few days shooting every one I could find, and managed to get about 10 of them, till one day as I'm stalking one in a tree in the front yard I heard an amplified voice say "Put the gun down and show me your hands!"
Three cop cars parked about three houses down from mine, and all the cops well protected behind the doors of their cars, just like on TV! I broke the rifle open, showed them it was an air rifle, then layed it down and walked away. When they saw it was an air rifle they relaxed considerably and as we talked they explained that it was illegal to shoot an air rifle in the city! News to me, as the sporting goods store I bought it from said it was legal - so I wound up taking it back and getting my money back. Moral of the story, check your local ordinances before buying a gun/shooting them.
I haven't had any problems with them since.
I have noticed tho, that nature does take care of her problem - just as the other poster related, one year we had a real surplus of them, and that summer I noticed a frequent appearance of two hawks. This year we've only had a few squirrels, and they're much fatter than normal. I think that means fewer tree rats sharing the same amount of food, which probably means we'll have a bumper crop of them next spring - it will be interesting to see what happens.
One last note, I've seen the same one in our back yard now for almost 5 years - his tail is mostly gone, whether from a predator or just the way he was born - that's how we recognize him - and I had no idea they lived that long! But we've been watching him since he was a pup!