In most cases if you don't have the clutch properly bled then the pedal will stay down. (It won't return).
These cars have no access hole so one can not see what actually happens. Of the various ways that a clutch won't disengage very few of them will show up on the pedal. The throw out bearing rides in and out on the shout of the trans. I have seen them jam due to lack of lubrication. That would be the only way that the pedal would resist movement. The act of depressing the clutch makes a ten inch plate move back a small amount. The disc is then free to move. Any malfunction that causes the movement to be non parrallel will only release one side of the disc. This is the normal problem. The springs in the rpessure plate fail or the disc fails in a way that bunches up the material in a thick spot. It takes very little dragging to accelerate the dics and input of the tranny.
If one wishes to see this effect take the car and place the trans in neutral. let the clutch out, now step on the clutch and pull it into reverse. If done quickly it will grind as the disc takes time to slow down. Now do the same thing and pull it into a forward gear. One should notice that it doesn't grind. The reason is that the syncronizer acts as a brake and stops the still spinning clutch. Go back to reverse and try it a few times you will get a feel for how much drag there is. Try it with the clutch just dragging a bit. With just the slightest drag you won't get reverse and yet you will get a forward gear because of the syncros.
Don't try this on a late model manual trans as they have syncros into reverse and you won't see this you will just burnup syncros.
Bosch Master, ASE Master, L1
33 years MB technician