Sunday night's crash near Greta killed 10 people, and nine others remain in hospital.
Thursday's depot raids by police investigators and National Heavy Vehicle Regulator inspectors involved the inspection of 20 buses at Linq Busline depots in Wyong on the NSW Central Coast and at East Gresford near Newcastle.
Seven defect and two infringement notices were issued after a cracked windscreen, oil leaks, inoperative seatbelts and vehicle lights and insecure seats were found.
Defect notices mean a problem needs to be fixed before the vehicle can be driven.
"The joint operation involved a comprehensive audit of documentation relating to fatigue, driver management, vehicle servicing and maintenance records, and safety management systems," a police statement issued on Thursday evening said.
Linq said in a statement that "one major defect identified in the fleet has been rectified" and minor defects were being rectified in accordance with the timelines set by the regulator.
On Thursday evening devastated family and friends of the victims of the wedding bus tragedy gathered near the site of the crash to grieve the 10 people who died and thank frontline workers.
Most of the 25 survivors treated in hospitals after the Sunday night crash at Greta have been discharged.
The nine who remain in hospital are in stable conditions, with seven at John Hunter Hospital and two at Sydney's Royal Prince Alfred Hospital, NSW Health said.
More than 900 donations have been made since Wednesday to a fund for survivors, victims and their immediate families, with almost $500,000 raised.
The community of Singleton has been hardest hit by the disaster, with seven locals among the 10 people killed when the privately chartered bus crashed following a wedding at Wandin Estate Winery.
Cessnock mayor Jay Suvaal said the community would come together on Thursday evening to support the loved ones of those lost in the crash and pay tribute to the first responders.
"We're a really tight-knit community that does come together and support each other in times of need," he told AAP.
Locals have offered accommodation and support for victims and their families.
"People are just dropping in things like cake and biscuits to our crisis centres to make sure there's food available for the people there," Mr Suvaal said.
Mourners continue to make the sad pilgrimage to a makeshift memorial at the crash site, which is strewn with a growing pile of flowers, cards and teddy bears.
Counselling and support is being offered at centres in Singleton and Branxton.
Health Minister Ryan Park said mental health services would remain available for as long as they were needed.
"What I do know about these types of traumatic and devastating events is that often it's not in the hours and days afterwards where people need additional support - it's often in the weeks and months," he told reporters on Thursday.
"They've been through unimaginable grief and suffering."
The insurer managing the crash compensation claims is being urged to ensure extended family and friends of the victims receive support.
Only those directly involved in the crash or who had suffered psychological trauma due to the death or severe injury of a close relative are eligible for support under the state's compulsory third-party scheme.
Slater and Gordon lawyer Doug Williams called on the insurer to show compassion to those who have suffered due to the crash.
"It's (the scheme) so limited that the close friends and the extended family as well as members of the small community where many of those killed lived would be ineligible to claim treatment," he said.
Many of the victims were closely involved with the Singleton Roosters AFL club and the AFL Central Coast has cancelled its seniors matches this weekend out of respect.
Sydney Swans players will wear black armbands during this weekend's match against the Lions in memory of the victims.
"We are deeply saddened by the horrific events over the weekend," Swans chief Tom Harley said.
The bus driver, Brett Button, 58, faced Cessnock Local Court on Tuesday charged with 10 counts of dangerous driving causing death.
Anyone wanting to support the families and injured with a donation is encouraged to visit www.rawcs.org.au.
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