I'm getting back into cycling after years of rarely riding a bike. I've got an old Trek Mountain Track 800 that I'm "rehabbing". I plan on riding it until I've got enough for a new bike. I'm not looking to drop a bunch of money on it, but in giving it a thorough wash, de-grease and lube, I noticed that there is an issue with the brakes. I haven't ridden it for about 14 years. The brakes are traditional cantilever style. The plastic part around the adjustment screw on the front brakes cracked and broke off last night... the brake on the right side works just fine, but the left side brake pad rubs on the wheel rim. Is this something I could easily fix (and pick up the part at the BS) or should I just plan on getting a new (and updated) brake system?