Had to replace the slave and did the master just in case in our 86 Toyota truck. I watched a video as well, pretty easy overall, though getting a wrench on the slave was a little challenge. Ours lost fluid, got mushy, and eventually quit engaging, it did not get stiff.
One note, be careful of the clutch pedal return spring and hold onto it well. Mine slipped out of my hand and disappeared under the dash. Fortunately, it still seems to work.
You might make sure the linkages to the master are all sound.