The problem with Bertha, the lady-named tunnel machine that's digging a $4.2 billion mega-project under downtown Seattle, isn't just that she hit an obstruction that stalled her for two months.

The problem is also that the machine itself is broken, the state says in a new announcement on the Washington State Department of Transportation's website. The seal to the central bearing that turns the cutterhead is busted. There's no timeline for fixing it. There's no estimate for costs or delay. After all, it took them months to even figure out what the problem was. But it's fair to say that with a dwindling overrun budget and three months of downtime already under its belt—the last two months of technical problems, plus a month-long delay last year during a labor dispute—this project (which we were promised by the governor, transportation officials, and the city council would be completed more or less on time and without cost overruns) is now veering into an uncertain future.

Here's part of the state's announcement:

For two months, the contractor on the SR 99 Tunnel Project, Seattle Tunnel Partners (STP), has been working to determine what caused the stoppage of the SR 99 tunneling machine on Dec. 6, 2013. WSDOT and STP have identified two contributing factors: a clogged cutterhead and high-temperature readings indicating there were other factors to explore. ...

After the cutterhead was unclogged, the contractor moved the machine forward an additional 2 feet and installed one of the concrete rings that line the tunnel. On Jan. 28 and 29, higher-than-normal heat sensor readings appeared like they did on Dec. 6, 2013. In the course of investigating the temperature readings, STP discovered damage to the seal system that protects the tunneling machine’s main bearing.

The main bearing is what allows the cutterhead to spin. It is similar to the bearing on the axle of a car, which is protected by a seal that keeps lubrication in and road grime out. The tunneling machine’s main bearing is protected by seals that function the same way - they keep the bearing lubrication in and the tunnel muck out. Investigations have shown that portions of the seal system have been damaged and need to be repaired or replaced. STP and its tunneling experts are working with the machine’s manufacturer to determine the best fix for this issue. They are currently assessing the extent of the damage and the best path forward.

The full statement is here. And, you know, I don't want to sound like subterranean Chicken Little—"The ground is caving in!"—but WSDOT officials have been reticent from the start of these problems in December. They've downplayed the seriousness of a stuck machine. And they've been silent on the real costs (such as how much of the contingency fund this will require and how we will pay for any overruns) or be honest about how far behind schedule they are. Maybe this will all be sorted out quickly at minimal cost! But the state's track record is obfuscation, growing delays, financing shortfalls, and a Pandora's box of logistical problems—so a speedy, affordable fix would be aberration.