No 'sorry' necessary. Much appreciate the help. A bit of a novice at this so will be taking on board any info I can get.JRising wrote:Sorry for the multiple-post spam, but another thought just whistled through my head...
It is possible on the old Gicar unit that's in your machine for it to try to fill boiler while you're pulling a shot. That Gicar doesn't monitor the position of the lever... One trick to rule out the possibility of the machine trying to "Boiler Fill" while you're brewing is to slightly overfill the boiler right before pulling a shot. When facing the machine, your right-hand side is the side where the boiler's level probe is. Lift the right side of the machine 3/4 of an inch or more up to an inch and a half and slip a cuttingboard or the handle of a kitchen-knife or something under the rear foot to hold it up like that until the boiler finishes filling to its new "slightly overfilled" depth. Then when you set the machine flat on the counter again, there's no chance of it trying to fill the boiler while you're brewing.
Further explanation. When brewing, the pump is forcing the water into the machine fighting against the backpressure of having to force water through the grounds in the portafilter. It builds 9-10 bar pressure to be able to force the amount of flow through the grounds that you see while brewing. If the Gicar decides to do a boiler fill, it opens a valve to the boiler which is only 1.2 Bar of backpressure to overcome, all of the flow takes that nice easy path, the pump noise changes as it overcomes less backpressure and there's no flow through the portafilter.
Does this maybe describe what you're experiencing?
If after doing the "Overfill before brewing" experiment, the problem goes away for a while, let us know. We'll get into cleaning your boiler fill probe and other suggestions that may limit the occurrence.
Can't look at this today, so will get back with my observations etc tomorrow.
BTW, the reservoir actually has 3 pipes, looks like the 2 you describe + a third which come out of the top of the reservoir, connects to nothing but runs vertically up the side. Also has a small plastic ball running inside of it.