DENVER -- City inspectors and the company that maintains the three-story Coors Field escalator that malfunctioned were working Thursday on a new set of tests designed to find out what caused the failure of an escalator.

They are trying to determine what caused the escalator to suddenly speed up on July 2, sending a crowd of people tumbling to the bottom, injuring 32 baseball fans.

Until now, both the city and Kone Inc., the company that manufactures and maintains the escalators, have been conducting their own investigations.

One focus of the city's investigation is the escalator's brakes, which apparently were unable to handle the load of passengers the system was carrying. The city had planned to conduct a weight test on the escalator Thursday. They wanted to place 15,000 pounds of metal on the escalator to measure how the system reacts to weight stress, the kind of stress that was applied on July 2.

But Kone Inc. objected, saying the full-load test was "irrelevant" to finding the root cause of the accident and could destroy important evidence.

"If a car's been in an accident and you try to measure its performance, until you repair it, you won't know what its performance was like prior to the accident," said Trevor Nink, president of Kone.

So instead of a simulation, the two sides will run a series of checks in an attempt to find out what went wrong. They won't, however, fully dismantle the brakes.

"We'll be taking a look at all the on-off safety switches, taking a look at the electrical current flow to the motor, to the braking system, things of that nature," said Julius Zsako, with the city's Community Planning and Development Agency.

The city said the weight test will still be conducted, but it's postponed for now.

"We still feel that the weight test is warranted, we still feel the weight test is necessary," Zsako said.

KONE disagreed, and issued the following statement later Thursday:

"KONE's top priority is the safety and well-being of the public and, as such, we are determined to find the cause of the July 2 incident at Coors Field. We are pleased that we have been allowed to move forward with most of the important diagnostic tests needed to uncover the facts.

The diagnostic tests were designed by our mechanical and electrical engineers in consultation with an independent escalator expert. Today's inspection will include a thorough examination of the automatic safety devices, a check of the lower end of the escalator where the most damage occurred, and conducting a number of tests and measurements within the safety braking system.

Unfortunately, the City still will not allow us to disassemble and thoroughly inspect the brakes. This seems a bit confusing given the fact that the City Inspector's report cites low brake torque as one of the possible contributors to this incident. We hope this will not impede our ability to ascertain the cause of this incident.

Upon completion of these tests, we will analyze the data and expect to have technical answers needed within several days to determine contributing factors and possible remedial action, if needed."

An expert in the field, who's not involved in this investigation, believes either the escalator brakes were improperly designed to handle a full load of passengers, or they were improperly maintained. He said there was no overloading.

"You cannot overload an escalator, period. Not with passengers," said escalator expert Carl White.

Until the investigation, is complete all seven escalators at Coors Field will remain closed. Fans coming out for one of the Rockies home games this weekend are reminded that they may need some extra time to get up the stairs or up the elevators.