Hydraulic Clutch failure

I have a 1995, V6. This problem kind of came out of the blue. I was finshing my plow route and and my last pass,all of a sudden the clutch pedal didn't come up when I tried to engage it. Thinking it was the Master Cylinder I changed it but that didn't correct the problem. I now have the clutch operation cylinder off wondering if I should change that too. I also see there is a clutch dampener that looks like it has moving parts. The clutch wasn't slipping so I don't think that is the problem. Took both the master cylinder apart and the operation cylinder apart and my untrained eye doesn't see anything out of the ordinary. The only symptom that has cropped up over the past couple months is I really have to get the clutch all the way to the floor to trip the interlock switch. Anybody have this problem before?

Could be moisture in the hydraulics freezing, just flush it through good, always flush the whole hydraulics during master cylinder replacement or slave replacement. Could be master cylinder, then could be the slave cylinder. Check all the mechanical parts quickly first. Sometimes plastic pieces/connectors break etc. Could also be the clutch springs and the bearing that rides against the clutch when you push it in and out. I would first suspect master cylinder and moisture in the system. Moisture becomes an issue especially when it freezes!