Leif,
Give a dog a bone and .............................................
http://www.markinsamerica.com/downlo...ll_en_v2_1.pdf
The instructions they should have sent with the replacement knob.
You should be able to knock out the plastic end cap with a drift and lets hope they have included a locknut. I would suggest a touch of loctite 242 on it when you do assemble.
Don