Well i got my sparky to come out and wire up my Bridgeport series 2 only problem was he didn't know how to program the inverter i have read the manual and its still being trouble

i started the inverter and tried to power on my BP series 2 and it made a humming noise coming out of the coils (think its coils unsure)

and would give slightly different humming if i changed the machine from forward to reverse

if anyone can figure on whats causing this hum or how to fix it it would b much appreciated.