After spending weeks searching for what might be blocking the Highway 99 tunneling machine, officials say there’s another problem: Bertha is running hot. Adding to the trouble, project managers say they don’t know why. High temperatures near the machine’s cutting face prompted contractors to stop mining after the drill advanced a total of 4 feet in test runs Tuesday and Wednesday. And that ended Bertha’s attempt to resume mining after an eight-week layoff. . . .I t took weeks for Seattle Tunnel Partners (STP) to pump away enough groundwater to safely allow an 11-day inspection of the front end, which...