Shad, I’m concerned this is Flash’s problem. The mass in her crop is pliable. I suspect she may be clogged further down, like the proventriculus, as you suggested. How do you feel about molasses flushes?The cocconut oil is to help with lubricating the proventriculus. It doesn't do a lot for the crop. Need to bear in mind what I wrote earlier about the position of the crop and what the crops function is. Essentially the crop is a storage place. But, healthy chickens have food moving from the crop, down the proventriculus and into the gizzard constantly. Often what are percieved as crop problems are problems with the provetriculus. A blockage here slows the whole system up and the crop while functioning, cant empty do to the blockage in the proventriculus.
According to Gloria my vet in Catalonia the majority of the slow crop and sour crop problems she has dealt with are due to blockages in the proventriculus. The oil helps stuff move through the proventriculus,much like oiling the vent of an egg bound hen. Lots of water is to help wash up the bits in the crop so they float to a hieght that allows themto enter the proventriculus and flush down to the gizzard.
Most cases of fully impacted crop need operating on to remove the blockage. In some cases some concoction may help to dissolve the mass that causes the impaction but obviously this depends on what the mass comprises.