Discovery's payload cannister is prepared for the STS-131 mission
After a system test that showed the valve had stuck, tests were conducted that subsequently showed the reading was a one-off and couldn't be reproduced. The impact of the valve failing during the mission is low, so the decision to proceed was taken after a unanimous vote by mission managers. Another minor issue of a potentially loose ceramic inserts around the heat shield tiles of the flight deck was also deemed low risk.
Keep an eye on Spacers as the launch date approaches.
Image credit: NASA/Troy Cryder