Back up Route FAILS

Question

I have no idea whats going on here. There are 4 routers involved, the main router configs are as follows and the others I have attached. I Need the router named Tower to redirect traffic back down the serial interface to the router named JCWAtoDowntown. The problem is the JCWAtoTower Router is in the way and redirects the traffic back to the tower when it receives the traffic from the tower because that is it's default gateway. What needs to happen to make the JCWAtoTower router redirect the traffic coming back from the tower and put it to the JCWAtoDowntown router.
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
hostname JCW
enable secret xxxx
memory-size iomem 25
ip subnet-zero
no ip domain-lookup
ip name-server x.x.x.x
ip name-server x.x.x.x
interface Tunnel1
no ip address
interface FastEthernet0
ip address 10.6.18.4 255.255.255.0
speed auto
interface Serial0
ip address 192.168.101.2 255.255.255.0
no fair-queue
service-module t1 clock source internal
service-module t1 timeslots 1-24
interface Serial1
ip address 192.168.100.4 255.255.255.0
ip accounting output-packets
no fair-queue
service-module t1 clock source internal
service-module t1 timeslots 1-24
router rip
network 10.0.0.0
network 192.168.100.0
network 192.168.101.0
default-information originate
ip classless
ip forward-protocol udp 5631
ip forward-protocol udp 5632
ip route 0.0.0.0 0.0.0.0 192.168.100.1
ip http server
arp 10.6.18.5 00c0.b607.d30b ARPA
line con 0
logging synchronous
line aux 0
line vty 0 4
session-timeout 60
Gateway of last resort is 192.168.100.1 to network 0.0.0.0
R 69.0.0.0/8 [120/2] via 10.6.18.2, 00:00:00, FastEthernet0
R 192.168.104.0/24 [120/1] via 10.6.18.2, 00:00:00, FastEtherne
t0
R 67.0.0.0/8 [120/2] via 192.168.100.1, 00:00:05, Serial1
10.0.0.0/24 is subnetted, 1 subnets
C 10.6.18.0 is directly connected, FastEthernet0
R 192.168.0.0/24 [120/1] via 192.168.101.1, 00:00:09, Serial0
R 192.168.1.0/24 [120/1] via 192.168.100.1, 00:00:05, Serial1
C 192.168.100.0/24 is directly connected, Serial1
C 192.168.101.0/24 is directly connected, Serial0
S* 0.0.0.0/0 [1/0] via 192.168.100.1

Answer 1

The default route for the 10.6.18.2(JCWAtoTower) is 192.168.104.1 (Tower) and it has a 2nd default route to 10.6.1.8.4 (JCWAtoDowntown) with a metric of 2.
If I shut off the S0 int on 10.6.18.2 the traffic redirects just fine,
On the Tower router there is a default route of 69.146.108.57 and a 2nd route 10.6.18.4 with a metric of 2, the problem is at the tower, when I shut off the Fa0 interface(internet) the traffic redirects to the JCWAtoTower router (the next router in line) and instead of passing through to the 10.6.18.4 (JCWAtoDowntown) Router it puts the traffic back to the tower because thats the default route. How can I get the JCWAtoTower router to recognize that the internet interface at the tower has gone down to allow the redirected traffic to now go to the 10.6.18.4 router?
Thanks in advance for your help and any configs.