Trains are running again after an earlier system-wide suspension, which began at around 5.15pm on Saturday, February 19.
A 30-minute service restarted on Sunday, with the first trains leaving the depot just after 8.15 am.
Trains between Airport and South Hylton are currently operating to the usual Sunday timetable after previous delays following the later start.
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There is a suspension between North Shields and Tynemouth after a wall adjacent to the track collapsed.
There should be a 15-minute service between Tynemouth and Chichester all day on Sunday, an updated posted on the @MyMetro Twitter account said.
John Alexander, Metro Operations Director, apologised to passengers for the disruption ahead of Saturday’s action.
He said: “We are forced to suspend the Metro service across the system on Saturday evening and early Sunday morning due to an industrial relations matter affecting our Control Centre.
“I am sorry for the inconvenience this will cause for many people.
“A small number of Metro employees in our control centre are refusing to work overtime or train colleagues to perform their roles.
"We have contingencies in place to protect our customers when this happens, but on this occasion we’ve exhausted all options, so we do not have staff available to operate Metro safely during one full shift from Saturday evening into Sunday morning.
“We are working hard with our trade unions in productive talks to resolve the outstanding issues there are within the control centre teams.
"This is an unprecedented situation and I very much hope it is not repeated. We are doing all we can to prevent that.”
The disruption came ahead of a line closure between St James and Tynemouth. No trains will run in either direction for five days from Monday, February 21, while overhead power lines are being replaced.
Replacement buses will be operating in the affected area and Metro services will return to this stretch of the line on Saturday, February 26.