I am experiencing leaking at the mast on my P 23.
Had anyone else had similar problems? Any advise?
Any photos? They might give us a better idea of what you are talking about.
"Leaking at the mast"
What are you actually experiencing? As Tom G notes, send pics.
Precisions are deck stepped masts. They aren't keel stepped, where the mast goes through the deck and down to the keel (far more common on big boats) and thus are likely to leak through the deck where there's usually a flexible boot of some kind to prevent leaking.
So, with a deck stepped mast, all you have are fasteners through the deck holding the mast step in place. Your first step would be to remove and reseal the mast step fasteners. I would recommend while you're at it, that you allow this area to dry, and then pot the holes with epoxy to seal any core: https://marinehowto.com/sealing-deck-penetrations-to-prevent-core-rot/ and then at a minimum countersink the holes so whatever sealant you choose to use (NOT SILICONE!!) has a better likelihood of remaining sealed: https://marinehowto.com/bed-it-tape/ Smearing goop around the mast step will not fix the issue; the only way to fix it is remove it and seal it properly. This goes for any other deck fittings.
Precisions are known to have issues with the chainplates leaking, leading to stains and rotten bulkhead down below. This is generally a needed repair about every 10 years or so. Some people dig out the old sealant and reseal with new 3M 4200 (I don't think 3M 5200 is flexible enough) but others have had very good success with Bed-it butyl tape.
The other possibility for a leak is if you have a cable connection for mast lights near the mast.
As previously stated photos help us see what might be happening.
As Brian S mentioned, you want to do the proper repair so it will last for many years. If water gets into the core below the mast, you could end up with a more extensive repair needed.
I second the note about wiring. I had a problem with leaks through the deteriorating rubber seal of my Hella deck plug. On replacement, I tossed the rubber gasket and used 4200. (Butyl tape probably would have worked, too). So far, so good.