E61 seems to run fine for most of the shot, then lose pressure? Goes from cone to individual drips... General routine?

[KCcoffeegeek]

Working with a new-to-me Expobar Leva Gr1 from 2011 that I assume has been sitting for a long time. This is a work machine. I have a 2019/2020 Quick Mill Carola Evo at home. The screen was really caked up, have replaced with a IMS precision shower screen. I backflushed with Cafiza about 4-5 times this morning and let it just sort of soak for a while, too, which didn't seem to do a whole lot. Replaced the gasket with a new silicone one and am using IMS-made 18g Baristapro basket with a very good-fitting tamper.

It seems like the flow out of this machine is weak compared to my home machine just running it before pulling a shot. It doesn't seem to be moving a lot of water through the grouphead so I'm wondering if something is clogged. I'll get a nice extraction for about 75% of the shot, starting as individual drips that come together as a cone, but after about the halfway point it seems to reduce in pressure/flow (I know these are different things) and the cone breaks up into 7-10 individual drips out of the portafilter for the rest of the shot. I assume it's losing pressure/flow? This happens every shot and has happened with two different coffees. The only thing different from my process at home is I took an unused Knock Aergrind to work to use as my grinder, but I tested it at home and the shots pulled nicely, so I don't think it's my grind. Coarsened up a little for a shot and it did the same thing.

Any ideas what's causing this behavior? I think this is a heat exchanger machine and I don't get steam out of the group when I turn it on before pulling a shot, if that means anything. Nothing aftermarket on this machine (no PID). The temp of the shot seems right. The flow from the hot water nozzle seems a little slow, too, but the Carola doesn't have steam or hot water so I have nothing to compare it to.

I'm wondering if there is routine maintenance I should do on the grouphead, like a refresh kit or something and just replace all the replaceables, or if there may be scale somewhere? I have a lot of experience with Gaggia Classics and with doing routine maintenance on my Carola, but I have had no problems with any machines I've ever had to try to diagnose. Is there a total strip down procedure I should just do where I clean out everything? If this was a Classic, I'd know exactly what to do. LOL

[Nunas]

Working with a new-to-me Expobar Leva Gr1 from 2011 that I assume has been sitting for a long time. This is a work machine. I have a 2019/2020 Quick Mill Carola Evo at home. The screen was really caked up, have replaced with a IMS precision shower screen. I backflushed with Cafiza about 4-5 times this morning and let it just sort of soak for a while, too, which didn't seem to do a whole lot. Replaced the gasket with a new silicone one and am using IMS-made 18g Baristapro basket with a very good-fitting tamper.

Sounds like you've done all the right things so far.

It seems like the flow out of this machine is weak compared to my home machine just running it before pulling a shot. It doesn't seem to be moving a lot of water through the grouphead so I'm wondering if something is clogged. I'll get a nice extraction for about 75% of the shot, starting as individual drips that come together as a cone, but after about the halfway point it seems to reduce in pressure/flow (I know these are different things) and the cone breaks up into 7-10 individual drips out of the portafilter for the rest of the shot. I assume it's losing pressure/flow? This happens every shot and has happened with two different coffees. The only thing different from my process at home is I took an unused Knock Aergrind to work to use as my grinder, but I tested it at home and the shots pulled nicely, so I don't think it's my grind. Coarsened up a little for a shot and it did the same thing.

I don't think it's the grinder. Sounds more like a dying vibe pump. Your two machines are quite similar, both HX vibe machines. Try doing a water debit test on both and compare. Also, use a blind basket and compare the pump pressure. The results might tell us something.
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I'm wondering if there is routine maintenance I should do on the grouphead, like a refresh kit or something and just replace all the replaceables, or if there may be scale somewhere? I have a lot of experience with Gaggia Classics and with doing routine maintenance on my Carola, but I have had no problems with any machines I've ever had to try to diagnose. Is there a total strip down procedure I should just do where I clean out everything? If this was a Classic, I'd know exactly what to do. LOL

You might pull the mushroom and see if there's any scale there. If so, there might be some in the boiler, but on an HX, the boiler scale isn't related to brew flow, unless the scale is right inside the HX. You might pull the fill-wire off the boiler, put some descaler in the reservoir, pump it through the machine by pulling a couple of shots, wait a while, repeat a few times, then flush with clean water. Pulling the fill wire off the boiler will ensure that you don't get any descale solution in the boiler (assuming you don't want any there at the moment ).

[another_jim]

... about the halfway point it seems to reduce in pressure/flow (I know these are different things) and the cone breaks up into 7-10 individual drips out of the portafilter for the rest of the shot

Most espresso machines, even ones in need of restoration, don't violate the laws of physics. Chances are that the fallen apart flow at the end of the shot is higher, in terms of grams per second, than the cone was. If the pump isn't damaged, this is necessary, since the puck's resistance is reducing, and that means the flow through it will increase. This is something you can measure.

If the flow is in fact increasing; it means the puck is breaking up rapidly. Chances are that the shower screen and dispersion screw just above it are in such bad shape that there are jets of water damaging the puck.

If in fact the flow is decreasing, then the only non-twilight zone possibility is that the pump is on its last legs, and giving out after 15 to 20 seconds run time.

[KCcoffeegeek (original poster)]

I relaxed the shower screen before I even used the machine, so it's definitely not that.