Whitelee, which is Europe's largest wind farm, was closed down last week following the discovery that a blade had broken off at the hilt from a 2.3MW turbine in the early hours of March 19.
ScottishPower said so far around 120 of the 140 turbines are up and running after a "detailed examination" into each one by Siemens engineers. It said the investigation into why the blade fell off was still ongoing.
Siemens has also refused to comment on possible reasons behind the incident. A spokesman said: "We don't have the final conclusion. What we can say is that most of the turbines are back in operation."
He said this is the first blade break on a Siemens since it started manufacturing its own blades in 2000.
No one was hurt or endangered as a result of the incident, which happened around 2am. However, Whitelee wind farm contains an extensive network of trails for walking and cycling as part of its multi-million pound visitor centre.