I just triple checked the linkage and behold, it isn't going all the way, which I didn't notice because I thought pulling on it by hand would suffice. I don't think that is the problem though as it is almost all the way. That brings up a question I have though.... is the only reason the linkages need to be adjusted to account for wear? It isn't like it is possible to. For them to loosen over time and change length. I had adjusted them as per the MB manual, but I don't think that accounts for the wearing of the balls and sockets. I'll continue reading up on the lift pump and the bypass valve and see what I can do