[GreenKeys] 28LP sprocket feed with vertical tab but no LF?

[Nick England]

Howdy men - I have been working my way through the 28 waterfall
printer set that I acquired some time back. It has a mix of typing
units, one of which appears to be a friction feed converted to
sprocket feed (but lacking a few parts). It has the vertical tab drum
which I have no experience with but figured I could just ignore.

Local LF works OK, but when I sent it a LF character nothing happened.
Upon investigation, I see the stunt box has no LF function
bar/pawl/lever. Imagine my surprise! Is this normal? If so. did that
mean this unit can only type on lines designated by the vertical tab?
So what triggers the vertical tab?

Nick England K4NYW
www.navy-radio.com