Welcome locosam and what a great first post.
Firstly, there wont be anything wrong with the machine so my advice would be NOT to do anything inside. There was nothing wrong with so called V2 and there certainly wasnt anything wrong with even the so called V1......how do you think they got such rave reviews in the beginning? Yes the early models were not pressure regulated, but that didnt stop them being a great domestic espresso maker right from the beginning.
Overflow over the top of the group handle on a Silvia means no more than.....overfilled coffee filter ie, you have over dosed it. It is a common trait for Silvia. Knock back the dose, and keep it consistent.
A small tip then:
if your "coffeeophile quality" coffee filter (basket) does not have the usual groove for the filter circlip near the top, DONT USE it while you work out the correct dosing height. Go back to the regular filter that came with the machine and use the groove as a guide. After you have dosed, settled and tamped, the finished level of the top of the puck should (for a Silvia) be no higher than the top of the groove. You should actually just see the top of the groove or be only just at a point whee you cant see the top of the groove. (Any more grinds than that and you are overdosed and will get leakage over the top of the group handle as yo described).
Once you get that down pat, by all means go back to your coffeeophile filter and seek the same finished level in that, which presumably will be harder for you to work out at first if there is not circlip groove to use as a guide....
Yes consistency and understanding in your technique is what you need, I can see not much else than technique related issues in your questions, and all you have to do is take a lesson. Pay someone, and cut immediately to the chase. All will be well!
And did I say....leave the inside of the thing alone...if not for any other reason, there isnt much point putting a band aid on your leg to see if it might help your sore throat, and I cant see anthying to do with OPVs and delivery pressure in your questions* :)
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