Recently my Procon pump seized and I had to replace it. The first replacement came from a parts vendor as a replacement for my machine's pump but by a different manufacturer (Hydropure) and rated at 140 gph, it was noisy so I replaced that for a Hydropure rated at 16 gph. At first everything was perfect. The pump ran quietly and brew pressure was easily set. This morning I noticed the brew pressure had dropped to about 4-5 BAR and no matter how I adjusted the pump, I couldn't get the pressure to increase even with a blind basket in place. When the machine came to rest, the pressure gauge would show the increase to about 12 BAR which is normal.

I haven't really had time to diagnose anything so there may be a simple solution. I'm hoping someone here can chime in with some ideas about the cause.

Perhaps something stuck in the pump's bypass mechanism that's preventing it from closing?

I wonder if I can just remove the set screw and clean the parts out? Has anyone else tried this?

I don't know about Hydropure in particular, but the bypass in the Procons can be disassembled and cleaned.