Okay it is twist , with a twist .....i ll try to explain .
One thing it modifed . The transmission slides into ( when it threaded in) the floting top brass tube ( Not glued in ) .
The tube has about 1/4 in plug that has been drilled the size of refill .
The top is notched for the clip so it does not spin . It his held in place with a cap that has beed drilled .
That is glued in with a peace of cut tube ( Just long enuff to hold it - short ).
The tube with the refill glued in , is slipped into the pen extending through the top . Not cutting the refill till your ready for the top cap that cover the other one that has been drilled .
The top cap is drilled for the refill to be glued on . The one that twist the brass tube. The tube that is not glued in ...The one in the upper part with the refill glued in the plug . Now screw the transmission in , it pushes into the floting tube .
Okay a twisted slimline .......
If i left something out , let me know ill try to explain .
David