WOBURN (CBS) – National Grid union workers were protesting again Wednesday while the company works to fix a mistake some believe wouldn’t have happened if it wasn’t for the lockout.

National Grid says Woburn homeowners who have been living without gas since Monday should have service restored Thursday.

A replacement worker accidentally overpressurized a line. The mistake is putting more pressure on National Grid to end the lockout, now entering its fourth month.

“We don’t believe that would have happened if we were working,” said USW 12012 President John Buonopane.

Locked out workers were protesting outside of the Prudential Building in Boston. Both sides appear to be very far apart.

“They want a two tiered benefit system for new hires,” said Buonapane. “So anybody coming into the company, they don’t want them to have a pension anymore.”

A spokesperson for National Grid tells WBZ instead of a pension, new employees would be given 401Ks. The company would match a certain percentage.

“People who do this kind of work day in and day out decade after decade, they seriously, seriously get banged up,” said Joe Kirylo, President of Boston Gas Workers Union. “Their shoulders go, their backs go. Sometimes they have to go out on a disability pension.”

Healthcare plans, bidding rights and outsourcing jobs are also hang-ups in the negotiation.

The lockout started at the end of June. National Grid telling WBZ they are frustrated by the lack of meetings since then.

Union president John Buonapane says after the incident in Woburn, he hopes National Grid will value the employees more. The two sides meet again on Friday.