You definitly need a rebuild on the master cyl. Fluid is bypassing the inner cup. It is easy to do. Take the big nut off the back & remove the snap ring from the front. Disasemble the parts & lay them out as they come out so you can put it back the same way. Hone the cyl. & check for any pits. If the pits wont hone out you need to buy a new cyl. The kit has all new parts except the spring. Put the new check valve on the old spring.e sure & put the thick metal washer back on between the piston & snap ring. You will probably have to remove the clevis from the rod to get the new boot on. This is a good time to clean the threads up good so it will be easy to adjust. Adjust the rod so you have a tiny amount of freeplay before the pedal starts pushing down the piston. There is a small funnel shaped hole in the reservoir with a tiny hole in it. Make sure that hole is open. A piece of tag wire works good. You can put a little silicone grease on the rubber parts or use brake fluid as a lube.Bench bleed the cyl. before you put it on.
