NASA engineers hope to launch the shuttle Discovery around Sept. 25, officials said Monday, pending final resolution of two pesky but apparently minor problems. Richard Kohrs, a top shuttle manager in Houston, said a firm launch date probably would be recommended to NASA management in Washington by Tuesday. Sources said the launch date is likely to be a compromise between Sept. 25 and 29, the choice of engineers at the Kennedy Space Center in Florida. The only unresolved issues involve a tiny hydrogen leak and data indicating two valves in the ship's engine compartment opened slower than expected during a main engine test firing Aug. 10. Additional tests will be conducted this week.