The brushes are the energising feed to the rotor, initially powered from the battery; there should be some voltage there.No voltage reading at two terminals coming out from brushes (brass slip rings)
This may be a dumb idea, but are you sure the motor is driving the welder rotor? I mean, is the rotor turning? Maybe as simple as the flex coupling is broken between motor and welder.Thank you to both reply’s, firstly, the engine starts, runs, idles and high revs fine, no issue.
This now points to the fault being in the positive feed to the brushes for the field. (Not the negative side as I thought when I only read as far as where you gave the voltage at the brush terminals. I had assumed that this was at the brush terminals with the wires connected to them.)Brushes Terminal Testing with wires connected:
W/ Switch on- Low. High
1. POS terminal - 0.278. 0.258
2. Neg terminal - 0.280. 0.261