From the Maitland Mercury report:
Minutes before 2am on December 19, 1980, Maitland Woolworths was bombed.
Located in High Street at the time, next to the Westpac Bank, the blast caused $300,000 of stock damage.
A bomb had been lowered through a vent near the back car park of the variety shop.
Police were aware that Woolworths at Warilla had also been bombed with gelignite using a timer attached, and it too had been lowered through the roof.
Full article available at Maitland Mercury, 19 Dec 2016.