Hello and thanks for your insight.

I have a mint Rancilio S24. I'm the original owner. I bought the machine approx. 21 years ago. It's super clean and well maintained. I've replaced all the internal silicone tubing as well as the steam valve. I've also replaced the Water Level Adjustment Pressure switch thinking it was the source of the issue I am experiencing. The replacement part didn't solve my problem.

Basicilly the machine is on all day. I try to keep the water tank as full as possible. In fact the tank water level never drops below 50% capacity. As I said all silicone tubes are new, flexible - and unobstructed.

My issue is the machine constantly attempts to refill the boiler while I'm brewing or when steam valve is open. I'll purge the steam wand, flush the group head - and attach portafilter. I'll activate brew and within 4 or 5 seconds into the cycle the coffee flow will stop. The pump runs indicating that the boiler is replenishing. Coffee flow resumes after a few seconds.

In my opinion the machine should not enter the refill mode when the brew switch is active. Maybe I'm off track?

I understand that it's normal for the machine's boiler to cycle/refill throughout the course of the day. OTOH my machine enters this mode at abnormal intervals.

As noted I replaced the original Level Adjustment Pressure switch. It was fairly brittle. The machine still performs erratically after part replacement.

I can pull great shots with this machine. And the steam pressure is excellent. I'm wondering if there is something I can check or if there may be a faulty part that is causing the machine to stall to refill boiler while brewing and/or pushing steam.

Thanks again.
-paulie.