boublanc: That's a beautiful mod, something very much worth investing in the spare parts for to attempt.

Geo: Its hard to say when the problem started, I noticed it off and on over time, but it only became consistent as my techniques improved. Overall, its only until I started following the advice on this forum did I form a benchmark of quality to base my previous experience on.

As for the grinder, thats been fully expected, although my grind settings to vary wildly depending on how the beans are behaving. Its not tape modded, but I just happen to have a roll of teflon tape on hand from a previous project, the blades however, are pristine.

The shot quality is still marginal, but I dont have much to compare it to, what im getting is still far better then anything coming out of the cafes here, but this isnt a city where one would find a 'serious' coffee bar.

I've had a tendency to put a lot of attention on the polishing part, its one variable I didnt think to change. I'll give it a go once I pick up some new beans tomorrow. I have 250g of Kenyan AA but its 3 weeks off the roast and probably wont be all that consistent. Thanks again for the input guys, much appreciated.

I had a similar issue once with a different machine. I did everything I could think of and it would still channel from the same location. In the end, it was me not the machine. One other thing you could try, tamp with the basket out of the portafilter or try tamping with the portafilter turned 180 degrees from your normal position. So if you tamp with the handle pointing at you, turn it around and tamp. Does the extraction start in the same spot, or did it move? I was unwittingly tamping harder on one side than the other. The tamp would be level but the pressure was off. The extraction problem would move if I tamped with the portafilter in a different position. In the end, I had to pay more attention to my tamp and it correct the problem. I started dosing a little less, grinding a little finer and tamping lighter. I literally tamp with three fingers holding the tamper top. It still haunts me now and then but the issue is much improved now.

I've been having mild success since starting this post. carefully examining use of the WDT method, and as per a previous suggestion, laying off on the final polish of the tamp. The flow rate has improved, the channeling has since moved location but I did nail a very good flow rate with improved flavor. Im tossing in a scale purchased from an electronics store to help further nail problems which may arise from dosing.

The only thing which may help further is the inclusion of a bottomless filter, which may be some time off, but from what I see well worth the investment.

Thanks again for the responses.

You lost me, how can you see that the shot is channeling or flowing faster at the 10oclock position if you don't have a bottomless portafilter?

Are you sure you're talking about channeling as opposed to leakage from around the group gasket? It seems like you might be referring to leakage, since you were talking about maybe having problems with the PF locking lugs or the seal.

"Channeling" usually refers to what happens when water finds a weak spot in the coffee puck and runs faster through one part of the puck, resulting in an underextracted, bitter shot. But if you don't have a bottomless PF, I don't see how you could tell where the channeling starts.

However, if you're talking about leakage from around the outside of the PF, then the likely culprit is a worn out head gasket, or possibly a burr or imperfection in the PF or basket edge that would prevent a proper seal between the PF and the gasket. Your solution might be as simple as just replacing the gasket, or filing down a burr on the PF lugs.

I gauge channeling by examining the puck post-shot, with the same water etched trench penetrating halfway down the edge each time, in that 10 O'clock position. I was always under the impression that this was indicative of channeling, showing where the water punched through on the path of least resistance.

Maybe I'll take some pictures to illustrate.

Is this perhaps nothing at all and Ive been worrying about nothing?

Dan Kehn said "...if the puck's surface looks and feels basically the same each time, I believe you've exhausted the value of 'puckology.'"

Many have said "Pucks are compost"

'nuff said.

Looks like I was chasing unicorns. Good to know that at least what Ive been observing isnt end all regarding my efforts. I'll have to seriously look into that bottomless filter now, its the only way I think I can really clue this up and have my way with this unforgiving machine. Thanks again, sorry for the mis-communication in the OP.

Puckology has limited functionality. If you had a bottomless portafilter and were getting early extractions at that location as well as seeing the disrupted puck surface in the same location there may be something to it. One thing you should keep in mind, after the shot the 3 way opens. That portafilter goes from 130psi to 0psi in under a second. That will cause the puck to deform, not to say what you are seeing is not a product of channeling. Without a bottomless portafilter diagnoses is limited.

Update. After purchasing a scale, removing the retaining clip and dosing/tamping out of the PF my shots are coming out better then ever, with the same fissure occuring in that 10 O'Clock position, so it may be safer to say right now its an issue that is completely redundant. Pending funds, Im aiming at a bottomless filter to end this debacle once and for all.

Thanks everyone.