Volunteers were left distressed when they discovered thieves had ransacked the Canberra Railway Museum in Kingston on Boxing Day about 2.30pm.

The burglars swiped important parts from steam locomotive 1210, which brought the first train to Canberra 100 years ago.

The railway museum was placed into liquidation in November 2016 after its freight company – started to subsidise popular but expensive heritage train trips – collapsed, leaving more than $700,000 in debt.

But a new entity of railway enthusiasts recently took it over with hopes to reestablish the museum and a local rail network by Easter.

Those plans look set to be put on hold with the stolen items essential to getting the steam train back up and running.

The audacious thieves even returned again yesterday morning after being scared away by the neighbour's dog on Tuesday.

Director of the new entity taking over Canberra Rail Museum John Cheeseman said he suspected the thieves were after the metal - mostly brass - the items were made of .

"The pieces are about 140 years old and not something you can just go to Bunnings and replace," he said.

"If it was just a few tools we would not have been that upset, but the items they have stolen are basically irreplacable."

The fittings had been stripped from the steam train for restoration before the museum's closure in 2016 and stored at the site.

Volunteers had hoped to have the steam back running by Easter but now believe that is unlikely.

It's been a tough year for the museum, being closed for more than 12 months, but things were starting to get back on track.

"For a lot of these people our hobby for the past 30 years had basically come to a stop," Mr Cheesman said.

"We are still looking forward to getting it going again but it's going to be a lot harder."

ACT Policing are investigating the theft.

Anyone with information should call Crime Stoppers on 1800 333 000.