Sounds like you need to flush the system w/fresh fluid. Evacuate the master cyl, use a pin or needle to make sure the two holes in the floor of the master cyl are totally-clear of any residue/material, and reverse-flush the slave cylinder using the bleeder nipple there & a 60 cc syringe & a short length of clear plastic tubing hose-clamped to the bleeder nipple to flush fluid upwards into the master cyl reservoir until it's filled. Close the slave cyl bleeder nipple, slowly and gently squeeze the clutch lever, and you should witness a small 'geyser' of fluid spray-upwards from the small, forward master cyl hole closest to the clutch hose. if if does, then replace the master cyl cap & you should be good to go.
Your front master cyl hole, the smaller-diameter one, is plugged, and there is probably a lot of sludge in your fluid, which is thick-enough to block that tiny hole. Your clutch and brake fluids should be transparent, not opaque. Flush according to this and your troubles should be gone, assuming you don't have an internally-collapsed hose, which could also produce your symptoms. The only way you're going to know that if the reverse-flush doesn't fix your problem is to remove the hose and to try blowing through it, I usually use compressed air, but lung power will work in a pinch. There should be NO blockage to the airflow, if there is, replace the hose. Don't forget to check the rigid hose too, there may be an accumulation of sludge in it as-well. Blow it clean, after detaching it from the slave cylinder.
