Hi. New to the forum

my 2000 Cabrio needs a new antenna grommet. Picked one up but it appears like the internal antenna base has to go over the new grommet rather than pushing it up through the bottom of the grommet (unless I have to heat it up to get it in maybe?).

looking for advice on best installation method and if the antenna base unscrews to fit it over the grommet. Please attached pic.

Thanks in advance for any assistance.