Took the cover off of Kim's 79 CM400T to figure out why the brakes were so weak. The above is what I found. I already need to replace the white plastic cup since it is very weak and cracked from age so there's $30 from bikebandit, as well as the diaphragm and cover since the diaphragm is disgusting and the cover is warped another $30-$50. I need to decide if I should bother cleaning the above or just replace everything with a generic master cylinder from e-bay like this click here and get a custom stainless steel line.
What's the verdict from those who've been here before? Clean and repair or just replace and get a new hose to match the new master cylinder?