Six Hole Shower Holder Causes Massive Channeling on Gaggia New Classic

I’ve got my Gaggia New Classic for 3 months now. Shots were often inconsistent but getting better. But since I got my bottomless portafilter, I just couldn’t get anything right. 80%+ of my pulls were channeling like crazy and I ended up with 1:4 in 20s or so. I tried everything. Finer, coarser, different espressos, high doses, low doses, different tamping pressures, different basket sizes. Barely any effect. Only very high doses and high-pressure tamps made it a little better. Still awful.

1.5 kg of coffee later, I noticed that every puck looked the same: a massive hole at 1’o clock.

That made me curious. I checked the shower screen, cleaned it and did the same with the holder. Played with screw tightness. Checked water distribution and flow. Everything looked good. But then I remembered that I changed the plate holder from the stock 4 hole aluminum one to a 6 hole stainless-steel one. Not because I needed to, but because I got it in a set pretty cheap. More holes, more better - right?

After changing it back to the stock one the problem is gone. First I thought the 1’o clock hole aligns with the water stream. But that doesn’t seem to be the case. Maybe they are to far on the edge of the puck. To be honest, I don’t quite get it.

But at least I’m consistently getting decent coffee again.

By the way, I’m not the only one having this issue. I found a post on Reddit and a customer review on amazon.com.