I have not attempted the replacement of my gear selector knob.
I am interested in why you need to undertake this repair.
I may need to undertake this job, but as yet am unsure if its needed in my case.
In the recent code weather in the UK my selector has sporadically gone "slack". ie it still can be moved through the various position. The selected gear or setting is selected, but the selector will not stay in the selected position, and wants to flop down to the reverse position.
I can force the selector to have its normal "stiff" feel by flipping it forward and backwards quickly several times.
I have not found any posts regarding this fault on the site, your post is the only one I have come across that is vaguely related.