To bad John won't stand behind his product. Pretty disappointing since he has done so much for us in the past.
I'm hoping it's a case of the manufacturer John buys from not standing behind their product, so not much John can do (unless he manufactures them in-house). Quality control on a LOT of things (even critical medical equipment) has gone down the toilet. We fight with the OEM's when we get crappy parts, and in turn they fight with their suppliers (many OEM have other companies cast/manufacturer sub assemblies or parts for them as they do not have the capabilities in house). John may be changing his ways, or he may just be frustrated as some things are out of his control and he keeps getting beat on by customers and it's showing.
When places shut down and inventories were depleted (with a high demand), lots of places pushed volume over quality when getting back online to meet the demand. I have a feeling we will be dealing with this fallout for at least another year or two (more depending on how the world readjusts).
Whatever it is, as he is an OG and supporter of GM diesels, I'm hoping it's the latter.