The middle contact assembly is 2nd speed. The 3rd speed (1A) is the next one to the left. The one on the the far left is the interlock which puts all four batteries in series. Begin with testing 2nd speed operation then proceed with testing 3rd speed. Most traction faults are caused by high resistance in control circuit - switch, broken wire, bad connection. I've worked on this model for almost 30yrs and have replaced contact tips hundreds of times, but would have replaced less than 10 contact assemblies. The resistor has nothing to do with top speed. 1st speed goes through the resistor, 2nd speed goes through 1/2 of the resistor, 3rd speed bypasses the resistor and changes to 24v. The best tip that I can give when a 3rd speed fault presents, is test each individual battery and then do voltage drop tests on the power circuit and control circuit (fuse, door sw, key sw, brake sw, SAS sw, F/R sw, 2nd speed sw, 3rd speed sw, rab/turt sw, mast sw, interlock sw)