Gaggia Anima Prestige can't grind fine enough

I'm having trouble tuning in the grind on my month old Gaggia Anima. I'm consistently getting 8 second pours and thin under-extracted and sour espresso using the higher aroma setting, and on any grind setting. I have pulled enough shots for the auto-tuning of the dose to take effect.

I have tried grinding the same beans with my Baratza Virtuoso Preciso, and I can get a good 12-14s pour and full bodied espresso using 10-11g of coffee in the manual dosing slot with the right grind.

I have already adjusted the grind level control to go as fine as the stop on the grinder will allow (after trying all of the stock options, and following the WholeLatteLove video for how to access and adjust the grinder). I'm pretty confident that I am not seeing channeling, based on comparing the pucks with the preground pucks (auto-ground pucks are all coarser than the pucks from the good pour with manually ground beans).

Does anyone have a guide for how to get even finer grind from the grinder? Is there a way to move the stop, and/or will fully dismantling and cleaning things out possibly help?