Sorry for the poor description in my post. This machine has the Ferdco smooth plate with the needle guide in place of a feed dog. It is not loose. There is no slop in the linkages, or excessive wear in the needle bar. This machine has very few hours of use. Don't wear your church clothes around my machine as there is more than plenty of oil on the mentioned knuckles. Old timers used to tell me grease is cheap. Now I'm and old timer, so is lube oil.
I have adjusted the needle and walking foot timing, adjusted the presser foot, and that seems to have fixed the problem.
I'm going to stick my neck out here: Timing, Timing, Timing!
Thread size, thread brand, nylon/poly/bonded, needle size, to some extent tension, variation in thread path from spool to take up spring. While important, adjusting, changing these things are little more than tiny bandaids, if the machine is not totally in time!
Mine was not. Operator error. DIY mechanic error.
I have learned many things about these minor adjustments, that will help fine tune my stitching in the future. It seems that these adjustments are what takes a machine that "sews" and makes it in to a machine that "sews really well". That is my goal.
Just my opinion.
Thanks for your comments/suggestions, they all open up avenues for working through a problem.