Hi all. First time asking and not just enjoying reading quietly the brain power around here. Couldn't find an answer anywhere.

The connection ‏between the body of the steam tap and the boiler got a little loose and started to leak. This is a Stradivari from 2016 taken good care of. I got the La Pavoni special screwdriver and got the bolts inside the boiler tightened so it's no longer loosened, but the leak is still going. I try to add some silicone lubricant as suggested in a different question around here but still, the leak continues. Any suggestions?
Thanks a bunch.

Did you remove the nut or leave it on and just tightened?

There is a copper washer above the nut. It may have scale buildup and is not sealing.
It could also be that you don't have it the assembly tightened fully. When I rebuilt mine I had a difficult time finding the right tightness and also end point for the turn. Took me more than a few attempts. This is probably it considering how newish your Stradivari is.

Thanks! Yes, I removed the nut and found the washer. Everything looked fine, but I was afraid to over tighten it and cause a dent. Eventually, I used more silicone around the hole, which seems to have solved the problem for now.

Buy some new washers for use in the future. Copper and brass crush/sealing washers are soft, and when tightened in they squash into the sealing surface, but this squashing causes work hardening. You can anneal them so they are soft again by heating them red hot, but easier to just use new ones, especially on a problematic seal.

I'm still experiencing the leak issue. Where can I locate the necessary washers? Additionally, do you have any tips on properly securing this? It appears that every interaction with the steam tap slightly loosens it. Thanks!

It's a 12 x 7 x 1mm brass washer that you might find at a hardware store. Various Pavoni parts suppliers sell it (La Pavoni Part No. 31300). I've bought mine from Stefano's Espressocare (Stefano is an HB member and sponsor). He also rents a tool with the specific purpose of tightening and holding that nut inside the boiler on steam valve and the safety valve fittings.

If your boiler is deformed at the opening you may have a hard time getting it tight enough. If your boiler fitting comes loose easily as a result of manipulating the wand I think it needs to be much tighter at the fitting. Make sure all surfaces that mate with the fitting and the washer are clean and smooth. No sealant should be needed.