finally an update.checked brushes for arcing and general shape.lenght is within tolerance with minor variations on different brushes(+/_ 1mm) and no arcing when running.powering truck with a decent battery now.voltage doesn't drop to below 24v when under drive load.
sometimes and as before when turning sharply left or right(when steering switches are activated by steering cam) the drive motors will drop out.resetting the f/r switch will get things going again.drove it 3 blocks and all was good then parked it.the next day contactors drop out again at slightest touch of pedal.25.7v on battery so not a charge issue.will be looking at contactor detecting unit for proper voltage tomorrow.
is this truck supposed to hum(fairly loudly) when f/r switch is engaged and the pedal is not depressed?
if only i could find a SCC-02C EVS analyzer:(