Here is the result of my pondering the problem of the refill not advancing in the WS III. I pondered the situation and noticed the twist part of the tranny was down inside the main part. That is a no-no. The segmented blank was measured and was in spec according to the library spreadsheet at 2.21. I put the Cap/Pocket Assembly into the end of the blank. Then I slid the open end of the blank/Cap onto the shoulder of the Nib Assembly an put it on the pen press. OK but the twist didn't work to extend the refill past the nib. In fact, it didn't do anything. I measured the tube in the WS II kit and extra tubes, #147120, and they matched the dimensions on the spreadsheet for twist WS III and WS II. I dry fitted the WS II; note the position of the segmented blank on the WS II. Now note the distance between the acrylic blank and the shoulder of the nib on the WS II. There's something wrong, IMHO. Instructions for the two kits are identical except for the diameter of the respective bushing. There were references to a Sierra pen but didn't find anything; obsolete?