I need some feedback please. We use a Reprex II in our studio. During the last class, last 15 minutes the carriage would stop mid travel like it hit a brick. Checked all the usual culprits- something on the gear track, high furniture, bad lock up, etc. Even changed some furniture to make sure none of the form was too high. Could not find the cause. Then I looked inside the carriage and noticed the slotted “holding pin” (photo attached) sticking up high enough to catch the guide bar when the carriage reached one complete turn down the track. I was able to push it down so it cleared the bar and we finished printing. Later I went back and screwed it all the way down. It is part of what I would call a collar or clutch which is supposed to be free moving and part of the guide release mechanism. It did not seem that the main shaft had a groove for it to fit in nor should it be screwed all the way down because the collar could not move. It probably has a spring in it. My question is does any Vandercook have a similar mechanism and what is it function? Thanks.