The fourth unit of the Guru Hargobind Thermal Plant at Lehra Mohabbat village in Bathinda district also stopped functioning on Friday, leaving the entire 920-MW plant out of operation.A senior official said the latest shutdown could have been caused by technical issues. The development comes at a time when three other units of the plant have remained non-operational for nearly a fortnight.The 210-MW fourth unit had been the only operational unit at the plant and was generating around 167 MW on Thursday. Sources said the unit had also developed a snag recently but was restored subsequently.The senior official attributed the shutdown of the other units partly to operational difficulties following a strike by outsourced workers, who are demanding direct engagement with the Punjab State Power Corporation Limited.He said efforts were being made to restore the non-operational units.