I added a knot at the end of the carrier return cord, installed it, put on the mainspring and tensioned it. Next, I installed the escapement cord. Now, with the slight shortening of the CR cord, there is a bit more tension on the cords although the spring loaded tensioner on the side is not pulled in to the desired line yet.
The changes was enough so that even when the carrier slammed to the extreme left due to failure to unlatch the CR mechanism, the cord stayed on both drums. I could unlatch the mechanism manually then resume spacing or tabbing to get the carrier over to the right again.
I can see that the problem is a failure of the carrier to push the margin rack leftward, partly due to the air cylinder keeping the rack from absorbing all the energy. I think the rack isn't moving fast enough due to residual good on the margin rack pins which slide left and right.
|Margin rack, right side, top pivot cocks the rack to the right|
|Left side of margin rack, vertical lever connects to air piston to handle high speed carrier return|
|Full pivot for the left side of margin rack, piston rod at bottom goes to air cylinder offscreen to right|
|Air cylinder to handle the deceleration and cushioning of the high speed carrier return option|
I am very, very close at this point, I think. I hope. Things will move quickly when I get the CR to unlatch properly, so this is the top priority. First I worked on clearing as much lube and resistance out of the rack and air cylinder as I could.
It still doesn't pop back when released, instead kind of oozing. This is typical behavior of IBM mechanisms once the lubricants of the sixties became the tar pits of this century. All I can do, unless I totally disassemble the affected parts, dip them in mineral spirits and reassemble, is to work some clean new light lubricant (I use a very light Mobil One synthetic) into all the sliding and pivoting spots, hoping to displace the old gunk through repeated cycling.
Next, I saw that the unlatch isn't triggered until the margin rack is moved to almost its full leftward extreme, something that happens with manual operation using the handcrank wheel, but that doesn't work right when it is returning rapidly under power.
|white plastic is pivot for unlatching the CR mechanism, when pushed by the vertical bar to its right|
|The bracket at the right of the margin rack with its vertical bar|