i just bought a 1978 garelli rally sport with a lot of little things wrong with it. I've taken care of most of the problems now and it runs great. I was wondering however, about my rear brake. It does not work. I spin the tire with my hand and push on the brake shaft that the cable is connected to; and it only slows the tire a small amount. the front brake, however- is very responsive when put to the same test. Do you think I just need to replace the shoe? Also, I noticed my carburator has no air filter, how bad is this for the engine if i just ride on city streets and stuff? Also, is there any way to make my own air filter instead of ordering online and having to deal with all that?