I finally did it, using intrepid510’s walk-through as a guide (thanks, man). With all the encouragement here (X, Y) and elsewhere concerning the importance of giving yourself a little margin for error by bringing the pressure down, my resistance was wearing thin. An Amazon credit removed the final obstacle, namely my own cheapness, so the parts were ordered Monday. They arrived yesterday, and within half an hour I’d assembled my gauge, determined my Classic was running at 170 psi (!), and adjusted it to 140 static. Today I pulled 2 shots of fresh Olympia Big Truck and noticed a marked improvement. Success!
For others still on the fence about doing this mod, I figured I’d add a few details from my own experience to the collective wisdom pile here.
Removing the portafilter’s double spout:
Personally, I didn’t need a vise (lucky me). Like Eric, I just stuck a Phillips screwdriver through the holes on either side of the spout and applied some muscle. I won’t put it back on either—no need, as I never split shots.
I opened up my machine prior to placing an order for parts, and I’m glad I did. First and foremost, a dry run is a good way to make sure you have the right tools before you need them. In my case, I discovered that (a) the extender I’d planned to use with my socket wrench didn’t fit my 17 mm bit, and (b) the hex key I’d thought was 5 mm actually wasn’t. No worries—a small adjustable wrench did, indeed, work fine for removing the nut atop the OPV valve, and a T30 Torx wrench was the perfect stand-in for that hex key when adjusting the OPV.
The gauge and coupling I used are the same ones that intrepid510 posted links to originally. They're cheap and effective. If you want a gauge that doesn’t need a coupling, this one was recommended to me. If you’re fussy about precision and want a liquid-filled gauge to eliminate needle bounce (which I got essentially none of, for whatever reason), here are two others (A, B) that Tex from the Gaggia Yahoo group mentioned recently.
How to deal with leaks:
At first, I was getting too much leakage despite having used plumber’s tape on the joint between the coupling and the gauge. This is probably due to the fact that I couldn’t thread the two together completely. Frankly, I think it’s the coupling that’s the issue, but I was too lazy to go to the hardware store and find a new one (preferably one with an elbow), so I just torqued it in as best I could and tried again. The second time was the charm. That’s not to say there wasn’t still leakage; during round #2 it was simply more manageable. You probably can’t tell in the pic below, but enough water had dribbled down that the gauge was entirely filled with water, which had seeped into it through a gap in its steel housing. No harm done. Speaking of water, consider putting some paper towels down under the gauge, and *definitely* put a small glass under the drain pipe coming from the 3-way valve.
Adjusting the OPV:
In case it’s not obvious, turn it counterclockwise to reduce pressure as needed. One full turn did the trick for me.
And that’s it! Now there’s one less thing standing between me and the best espresso I can make. I consider this a team effort. Much appreciated, y'all.