EMBOSS explorer was broken in Debian 7 (Wheezy) because of an incompatibly with EMBOSS 6.4. The package was repaired with the second update (7.2). The development and maintenance of EMBOSS explorer have stopped for many years. If a new serious bug surfaces, we may need to remove the package rather than repair it. In consequence, do not hesitate to suggest us an alternative, or if you are developer and need EMBOSS explorer, to see how you can reinvigorate this project (currently on SourceForge).