Mine Safety and Health Administration acting district manager Joseph Tortorea said staff members were going to interact with as many miners as possible over the next two-week period, according to the Pittsburgh Post-Gazette.

“As with any device, if you don’t use it every day, or you don’t have any experience, if may appear difficult to use,” Tortorea said.

The issue came to light after Sago survivor Randal McCloy said in a letter that four of the 12 SCSRs deployed after the January 2 explosion were faulty, the paper said. Additionally, testimony was presented at last week’s public hearings in West Virginia on the incident that even the successfully executed rescue packs were not completely used, ranging from 28% to 79% of remaining air supply.

Investigators of the explosion, however, feel otherwise and aren’t convinced of the malfunction theory.

“The tests we’ve completed so far indicate that they did start when the miners tried to do that,” said the investigation’s team leader, MSHA’s Richard Gates.

“Exactly what happened, we don’t know at this point,” he was quoted as saying in the paper.

The SCSRs, all CSE SR-100s according to the Post-Gazette, are being put through additional testing by federal researchers; meanwhile, the victims’ families have asked for the packs’ identification information and manufacturing dates. PA Bureau of Mine Safety director Joseph Sbaffoni, meanwhile, said that additional questions have also surfaced that could shed light on the situation.

“Did the miners put them on right away? Or did they breathe in carbon monoxide and get disoriented? Maybe they weren’t thinking straight. Maybe they just passed out and stopped breathing,” he said.

All involved did agree that the design of the SCSR is in need of an update. “Why have we not improved these things? They’re basically the same as they were 20 years ago,” former MSHA Academy director Jack Spadaro said at the public gathering.