Replace external sealant around UPVC patio door

[mcprinter]

Have a little bit of mould inside
Noticed the external silicone has come away from the UPVC frame just above where the mould is.

Installed well over 20 years ago.
Redo with silicone or is it worth using something else like CT1? Any particular product recommended?
Happy to spend extra on a better product.

Thanks

 

[crank39]

Mould is from condensation, external silicone coming away in the same area could be coincidence

 

[mcprinter]

This is the mould and the state of the exterior seal.
Not too bad.

We have perfect fit blinds (clip into the glass rubbers) which get a fair bit of condensation on the glass when the weather is cold/damp.

I have some Zinsser Perm White and Bullseye.
I think this was painted with fairly standard emulsion a couple of years ago