Hi,
I've been using an unpressurised after market basket and handle with my Delonghi Dedica for a while. It makes just OK espresso. I dont think my grinder is up to scratch tbh.
I thought I'd try a pressurised basket, but for some reason the espresso sprays out of the spouts laterally, making a huge mess, as pictured. Obviously this didnt happen before.
Any idea why? I tried a finer grind, distributing the coffee better, and tamping harder and more evenly. No cigar.
(Why a pressurised basket? The best espresso I've ever had out of this particular machine was with the stock handle and stock pressurised basket. Why not use those then? Because the stock basket doesnt grip the handle well. It falls out into the knock box when you bang it. I hate this with a passion)
Sounds like some weird channeling problem to me. You could try going coarser, like others have suggested (since you prefer pressurised baskets) and try a needle distribution tool to even out the coffee grounds before tamping. Also there is no need to tamp it with excessive force, especially with a pressurised basket.