on the tubes...mine looked bad as well. Here my procedure:
1) remove the ruber hoses on both ends
2) get a 3 yard steal cable from any store like home depot etc. I used 5mm steal cabel.
3) bend the ends so they do look like a spider leg set
4) pull them through the pipes ..several times..
5) rinse with fresh water..
6) close the lower end with a plug.. old winde bottle cork
7) fill the pipes with phosor acit - I got a container for 10 USD
8) let it sit for 2 days (temp dependent)
9) clean the phosor out by washing it by rinsing with fresh water
10) use an air drier to dry the intter part of thepipes
11) fill paint into the pipes ...I used Rost on Metal stuff..as it really socks in
12) let the paint in the pipe sit for 10 minutes or so
13) drain the paint by unplugging the lower side cork
14) use a hot air gun to blow through
(you might do a second paint filling..)
hope you like this..