Rust was found on all four cables of a lift that plummeted to the ground on Saturday night, injuring seven people.
It had been maintained by Shineford Engineering and government engineers are scrambling to conduct safety checks on 248 other lifts the firm serviced. So far they have found rust on three other lifts to the extent that services had to be suspended.
The lift in a commercial building at 480 King's Road, North Point, fell to the ground when all four cables snapped after it had passed the first floor going up.
The seven injured - aged 30 to 82 - were still in hospital last night. One of them, an 82-year-old man, was in critical condition. Another was in serious condition and five were stable.
Alfred Sit Wing-hang, deputy director of regulatory services at the Electrical and Mechanical Services Department, said the department had inspected 38 of the 248 lifts that are maintained by Shineford. The cables of three were about 10 per cent narrower because they had rusted.
"They are not rusted to an extent that they would break, but they need to be replaced," he said. One was in the building where the accident occurred. The other two were in Kwun Tong.
The department has sent 20 staff in four to five teams to inspect the lifts, and Sit hoped the checks would be completed in one or two days.
Sit said there were signs of rust on the four cables of the lift that crashed on Saturday. He said the department would conduct a laboratory test on the cables and find out why they broke.
He said Shineford had told the department that the four cables were replaced one or two years ago. "But we totally cannot accept the fact that cables that were replaced one or two years would break," Sit said.
Patrons of a restaurant the lift served said it had not operated smoothly for years and many patrons dared not take it. The lift was boarded off yesterday.
The department has no plans to inspect every lift across the city because the accident was a "very rare" one, Sit said.
But after the department finishes the probe into the accident, the department would pass the report to all lift maintenance contractors. The department will then discuss with the contractors to see how maintenance can be improved, he added.
According to the latest contractors' performance rating report issued by the department, Shineford scored only 69 out of 100, ranking 29th among 36 registered contractors.
The department described the performance as disappointing. Two lifts maintained by Shineford were reported to have equipment failure last year.
One incident in September occurred in the Kwun Tong Industrial Centre, when a defective electrical component caused a fire. The other was in June, when a mechanical problem caused passengers to lose their balance.