After 3 weeks I finally got what I regard as a great print. Took a long time and lots of advice. Today I decided re-calibrate everything, check mechanics. Replace throat. Ease path of filament to extruder. Increase extrusion rate by a small amount. Reduce printing speeds all by about 15 percent from nominal in Slic3r. Drop temperatures, using PLA, extruder now at 200 and bed at 60. The biggest problem I found had nothing to do with the electronics, extruder etc, the alignment of the guide rods on the bed was out. All of this took about 6 hours doing 1 step at a time, and a few coffee breaks to cogitate.